It is necessary to sum the functional sequence F(t) by 'n', while at each step of summation it is necessary to take 'n' from another array n(t).

It is necessary to sum the functional sequence F(t) by 'n', while at each step of summation it is necessary to take 'n' from another array n(t) I mean nD(t).

%% initial conditions

global d k0 h_bar ksi m E;

Ef = 2.77*10^3;

Kb = physconst('boltzmann'); % 1.38*10^(-23)

T = 0.12:0.24:6.4;

m = 9.1093837*10^(-31);

Tc = 1.2;

%t = T./Tc;

t = 0.1:0.1:2;

nD = floor(375./(2.*pi.*t.*1.2) - 0.5);

D = 10^(-8); % толщина пленки

ksi = 10^(-9);

%d = D/ksi;

d = 1000;

E = Ef/(pi*Kb*Tc);

h_bar = (1.0545726*10^(-34));

k0 = (ksi/h_bar)*sqrt(2.*m.*pi.*Kb.*Tc);

C_2 = 0;

for n = 0:49

C_2 = C_2 + (1/(2.*n+1)).*k0.*real(sqrt(3601+1i.*(2.*n+1))-((1+1i)./sqrt(2)).*sqrt(2.*n+1)); % константа

end

%% calculation

F = f_calc(t);

plot(t,F, '-r');

%% F(t)

function F = f_calc(t)

global d k0 h_bar ksi m;

F = 0;

for i = 1:20

n = nD(1,i);

F = F + 1/(2*n+1).*(k0.*real(((f_p1(n,t)-f_p2(n,t))./2))+(f_arg_2(n,t)-f_arg_1(n,t))./d);

end

F = -F;

%F = -(1/d).*F;

%F = F - C_2;

end

function p1 = f_p1(n,t)

p1 = ((1+1i)./sqrt(2)).*sqrt(t.*(2.*n+1));

end

function p2 = f_p2(n,t)

global E;

p2 = sqrt(3601+1i.*t.*(2.*n+1));

end

function n_lg = f_lg(n,t)

global d k0;

arg_of_lg = (1+exp(-1i*d*k0.*f_p1(n,t)))/(1+exp(-1i*d*k0.*f_p2(n,t)));

n_lg = log(abs(arg_of_lg));

end

function arg_1 = f_arg_1(n,t)

global d k0;

arg_1 = angle(1+exp(-1i*d*k0.*f_p1(n,t)));

end

function arg_2 = f_arg_2(n,t)

global d k0;

arg_2 = angle(1+exp(-1i*d*k0.*f_p2(n,t)));

end

Answer 1

[Voss]

Redefine the function f_calc to take nD as its second argument. (You could also make nD a global variable.) See below:

%% initial conditions
global d k0 h_bar ksi m E;
Ef = 2.77*10^3; 
Kb = physconst('boltzmann'); % 1.38*10^(-23)
T = 0.12:0.24:6.4;
m = 9.1093837*10^(-31);
Tc = 1.2;
%t = T./Tc;
t = 0.1:0.1:2;
nD = floor(375./(2.*pi.*t.*1.2) - 0.5);
D = 10^(-8); % толщина пленки
ksi = 10^(-9);
%d = D/ksi;
d = 1000;
E = Ef/(pi*Kb*Tc);
h_bar = (1.0545726*10^(-34));
k0 = (ksi/h_bar)*sqrt(2.*m.*pi.*Kb.*Tc);
C_2 = 0;
for n = 0:49
    C_2 = C_2 + (1/(2.*n+1)).*k0.*real(sqrt(3601+1i.*(2.*n+1))-((1+1i)./sqrt(2)).*sqrt(2.*n+1)); % константа
end
%% calculation
F = f_calc(t,nD);
plot(t,F, '-r');

%% F(t)
function F = f_calc(t,nD) 
    global d k0 h_bar ksi m;
    F = 0;
    for i = 1:20
        n = nD(1,i);
        F  = F + 1/(2*n+1).*(k0.*real(((f_p1(n,t)-f_p2(n,t))./2))+(f_arg_2(n,t)-f_arg_1(n,t))./d); 
    end
    F = -F;
    %F = -(1/d).*F;
    %F = F - C_2;
end
function p1 = f_p1(n,t)
    p1 = ((1+1i)./sqrt(2)).*sqrt(t.*(2.*n+1));
end
function p2 = f_p2(n,t)
    global E;
    p2 = sqrt(3601+1i.*t.*(2.*n+1));
end 
function n_lg = f_lg(n,t)
    global d k0;
    arg_of_lg = (1+exp(-1i*d*k0.*f_p1(n,t)))/(1+exp(-1i*d*k0.*f_p2(n,t)));
    n_lg = log(abs(arg_of_lg));
end
function arg_1 = f_arg_1(n,t)
    global d k0;
    arg_1 = angle(1+exp(-1i*d*k0.*f_p1(n,t)));
end
function arg_2 = f_arg_2(n,t)
    global d k0;
    arg_2 = angle(1+exp(-1i*d*k0.*f_p2(n,t)));
end