fzero with two variables and an array of elements in a loop

Hi, thank you in advance.

There are two variables x and y, as well as a changing parameter T_array. I am now using the fzero to solve the system of nonlinear equations.

However, in the second section, BB(y,T) includes A(x,T) in the first section. Below is the code.

There is error "Operands to the logical and (&&) and or (||) operators must be convertible to logical scalar values." I guess it is because of the wrong defintion of A(z,T).

Could you please revise it? As I am using the fzero methond, it will be better if you can provide a better method.

p.V0=1e-6;
A=@(x,T) 4e17.*exp(-25619./T).*(x-0.02).^2./(0.2-x).^3; % A
B=@(x,T) 5e7.*(2.908-1.154.*x)./(0.86+0.6924.*x);
C=@(x,T) 166980.*B(x,T).^1.7.*exp(-25619./T).*(x-0.02).^2./(0.2-x).^2;
fx =@(x,T) 5e-5.*(A(x,T)+C(x,T))-p.V0;

options=odeset('Refine',1,'RelTol',1e-20,'InitialStep',1e-7,'MaxStep',3e5);
T=linspace(273.15,700,500);
for k=1:length(T)
   fun=@(x)fx(x,T(k));
  z(k)=fzero(fun,0.06,options);
end

p.V1=1e-7;
AA=@(y,T) 4e17.*exp(-25619./T).*(y-0.02).^2./(0.2-y).^3;
BB=@(y,T) 5e7.*(0.6+2e-5.*T.*log(AA(y,T)./A(z,T))+1.154.*(0.2-y))./...
            (1-(0.6+2e-5.*T.*log(AA(y,T)./A(z,T)).*1.154.*(0.2-y)); % A(z,T) is related to the second line
CC=@(y,T) 166980.*BB(y,T).^1.7.*exp(-25619./T).*(y-0.02).^2./(0.2-y).^2;
fy =@(y,T) 5e-5.*(AA(y,T)+CC(y,T))-p.V1;

for k=1:length(T)
  funn=@(y)fy(y,T(k));
  w(k)=fzero(funn,0.06,options);

% figure  
plot(T,w,'k-',T,BB(w,T),'r-')

Answer 1

[Torsten]

p.V1=1e-7;
AA=@(y,T) 4e17.*exp(-25619./T).*(y-0.02).^2./(0.2-y).^3;
BB=@(y,z,T) 5e7.*(0.6+2e-5.*T.*log(AA(y,T)./A(z,T))+1.154.*(0.2-y))./...
    (1-(0.6+2e-5.*T.*log(AA(y,T)./A(z,T)).*1.154.*(0.2-y)); % A(z,T) is related to the second line
CC=@(y,z,T) 166980.*BB(y,z,T).^1.7.*exp(-25619./T).*(y-0.02).^2./(0.2-y).^2;
fy =@(y,z,T) 5e-5.*(AA(y,T)+CC(y,z,T))-p.V1;
for k=1:length(T)
    funn=@(y)fy(y,z(k),T(k));
    w(k)=fzero(funn,0.06,options);
end

[Mei Cheng]

@Torsten thank you very much! it works perfect!

[Mei Cheng]

@Torsten Hi, I am very sorry to bother you. Below is revised code, but there is still a few problems as shown. It cannot work properly. Also, x or y may exceed the range of 0.02-0.2 sometimes.

T=linspace(273.15,700,500);

p.V0=1e-6;
A=@(x,T) 4e17.*exp(-25619./T).*(x-0.02).^2./(0.2-x).^3; % A
B=@(x,T) 5e7.*(2.908-1.154.*x)./(0.86+0.6924.*x);
C=@(x,T) 166980.*B(x,T).^1.7.*exp(-25619./T).*(1-x./0.2).^(-2);
fx =@(x,T) 5e-5.*(A(x,T)+C(x,T))-p.V0;

options=odeset('Refine',1,'RelTol',1e-20,'InitialStep',1e-7,'MaxStep',3e5);
for k=1:length(T)
   fun=@(x)fx(x,T(k));
  z(k)=fzero(fun,0.19,options);
end

Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.4005e-27i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.877e-27i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.5109e-27i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.3528e-27i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.4691e-27i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-5.9465e-27i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-7.8985e-27i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.0473e-26i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.3862e-26i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.8318e-26i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.4164e-26i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.1823e-26i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.1839e-26i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-5.4918e-26i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-7.1968e-26i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-9.4159e-26i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.2299e-25i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.6041e-25i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.0887e-25i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.7155e-25i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.5249e-25i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.5686e-25i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-5.9123e-25i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-7.6397e-25i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-9.8571e-25i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.2699e-24i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.6337e-24i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.0986e-24i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.6919e-24i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.4481e-24i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.4104e-24i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-5.6333e-24i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-7.1853e-24i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-9.1523e-24i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.1642e-23i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.4788e-23i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.876e-23i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.3766e-23i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.0069e-23i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.7993e-23i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.7943e-23i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-6.0422e-23i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-7.605e-23i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-9.5599e-23i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.2002e-22i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.505e-22i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.8847e-22i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.3575e-22i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.9452e-22i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.6749e-22i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.58e-22i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-5.7012e-22i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-7.0886e-22i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-8.8032e-22i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.092e-21i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.353e-21i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.6745e-21i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.07e-21i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.5561e-21i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.1527e-21i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.8844e-21i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.7806e-21i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-5.8772e-21i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-7.2176e-21i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-8.8541e-21i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.085e-20i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.3282e-20i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.6242e-20i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.9841e-20i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.4213e-20i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.9518e-20i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.5949e-20i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.3736e-20i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-5.3157e-20i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-6.4544e-20i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-7.8292e-20i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-9.4876e-20i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.1486e-19i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.3892e-19i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.6787e-19i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.0265e-19i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.444e-19i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.9449e-19i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.545e-19i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.2636e-19i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-5.1232e-19i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-6.1505e-19i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-7.3771e-19i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-8.8405e-19i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.0585e-18i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.2662e-18i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.5134e-18i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.8072e-18i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.1563e-18i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.5706e-18i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.0619e-18i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.644e-18i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.3331e-18i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-5.1483e-18i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-6.1118e-18i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-7.2497e-18i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-8.5925e-18i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.0176e-17i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.2041e-17i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.4237e-17i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.682e-17i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.9857e-17i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.3423e-17i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.7608e-17i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.2516e-17i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.8268e-17i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.5002e-17i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-5.2883e-17i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-6.2097e-17i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-7.2862e-17i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-8.543e-17i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.0009e-16i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.1719e-16i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.371e-16i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.6029e-16i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.8726e-16i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.1862e-16i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.5505e-16i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.9734e-16i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.4641e-16i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.0329e-16i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.692e-16i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-5.455e-16i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-6.3379e-16i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-7.3587e-16i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-8.5383e-16i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-9.9005e-16i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.1472e-15i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.3285e-15i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.5375e-15i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.7781e-15i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.0551e-15i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.3738e-15i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.7401e-15i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.161e-15i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.6442e-15i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.1988e-15i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.8347e-15i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-5.5636e-15i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-6.3985e-15i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-7.3543e-15i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-8.4478e-15i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-9.698e-15i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.1127e-14i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.2759e-14i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.4621e-14i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.6746e-14i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.9168e-14i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.1929e-14i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.5072e-14i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.865e-14i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.272e-14i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.7348e-14i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.2607e-14i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.8579e-14i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-5.5358e-14i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-6.3048e-14i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-7.1769e-14i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-8.1651e-14i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-9.2845e-14i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.0552e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.1986e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.3607e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.544e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.7511e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.9849e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.2488e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.5465e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-2.8822e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.2604e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-3.6865e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.1661e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-4.7059e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-5.313e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-5.9954e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-6.7623e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-7.6236e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-8.5905e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-9.6754e-13i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.0892e-12i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.2256e-12i.)
Check function or try again with a different starting value.
Exiting fzero: aborting search for an interval containing a sign change
    because complex function value encountered during search.
(Function value at -1.7556 is -1e-06-1.3785e-12i.)
Check function or try again with a different starting value.

p.V1=1e-7;
AA=@(y,T) 4e17.*exp(-25619./T).*(y-0.02).^2./(0.2-y).^3;
BB=@(y,z,T) 5e7.*(0.6+2e-5.*T.*log(AA(y,T)./A(z,T))+1.154.*(0.2-y))./...
            (1-(0.6+2e-5.*T.*log(AA(y,T)./A(z,T)).*1.154.*(0.2-y))); % A(z,T) is related to the second line
CC=@(y,z,T) 166980.*BB(y,z,T).^1.7.*exp(-25619./T).*(1-y./0.2).^(-2);
fy =@(y,z,T) 5e-5.*(AA(y,T)+CC(y,z,T))-p.V1;

for k=1:length(T)
    funn=@(y)fy(y,z(k),T(k));
    w(k)=fzero(funn,0.19,options);
end

Error using fzero
Initial function value must be finite and real.

% figure  
plot(T,BB(w,T)./5e7,'k-')

[Torsten]

Syntax erros are corrected (see above).

I changed

BB=@(y,z,T) 5e7.*(0.6+2e-5.*T.*log(AA(y,T)./A(z,T))+1.154.*(0.2-y))./...
            (1-(0.6+2e-5.*T.*log(AA(y,T)./A(z,T)).*1.154.*(0.2-y)); % A(z,T) is related to the second line

to

BB=@(y,z,T) 5e7.*(0.6+2e-5.*T.*log(AA(y,T)./A(z,T))+1.154.*(0.2-y))./...
            (1-(0.6+2e-5.*T.*log(AA(y,T)./A(z,T)).*1.154.*(0.2-y))); % A(z,T) is related to the second line

Hope this is correct.

Problem-related errors (equations, solutions with imaginary part or NaN,Inf or -Inf values, initial conditions,...) are your part.