what does the error mean "Index in position 2 exceeds array bounds (must not exceed 1). Error in heat2 (line 116) if abs(Qforced(r,c) - Qfree(1,iterations)) < 0.001"

line 116 is underlined below

Tamb = linspace(261,283,10); %in Kelvin

Vwind = linspace(2.778,19.44,10);%in m/s

Tfree = linspace(150,308,10000); %in Kelvin

%constants

dia = 0.3; %in m

length = 1.8; %in m

Thum = 308; %in Kelvin

grav = 9.81; %m/s^2

k250 = 0.02227;

k300 = 0.02624;

dens250 = 1.4128;

dens300 = 1.1774;

visc250 = 1.5990*10^(-5);

visc300 = 1.8462*10^(-5);

Pr250 = 0.722;

Pr300 = 0.708;

r = 1;

c = 1;

hforced = zeros(100);

hfree = zeros(100);

Twind = zeros(100);

Qforced = zeros(10);

Qfree = zeros(10);

while r <= 10

while c <= 10

Tfilm = (Thum + Tamb(1,c))/2; %film t in Kelvin

%interpolation k, dens, visc, and Pr

k = ((k300-k250)/(300-250))*(Tfilm-250)+k250;

dens = ((dens300-dens250)/(300-250))*(Tfilm-250)+dens250;

visc = ((visc300-visc250)/(300-250))*(Tfilm-250)+visc250;

Pr = ((Pr300-Pr250)/(300-250))*(Tfilm-250)+Pr250;

%to get forced convection

Re = (Vwind(1,r) * dens * dia)/visc;

%if Re

cf1 = 0.0266;

nf1 = 0.805;

Nud = cf1*(Re^(nf1))*Pr^(1/3); %40,000<Re<400,000

%end

hf1 = (Nud*k)/dia;

%to get free convection

Beta = Tfilm^-1;

Gr = (length^3*(Thum-Tamb(1,c))*(dens^2)*Beta*grav)/visc^2;

Ra = Gr*Pr;

if Ra >= 10^4 && Ra <= 10^9

cf2 = 0.59;

mf2 = 1/4;

else if Ra > 10^9 && Ra <= 10^13

cf2 = 0.1;

mf2 = 1/3;

end

end

Nuf = cf2*(Ra^(mf2));

%end

hf2 = (Nuf*k)/length;

%to get wind chill temp

Twd = Thum - (hf1*(Thum-Tamb(1,c)))/hf2;

Qforced = hf1 * (Thum-Tamb(1,c));

Qfree = hf2 * (Thum-Tamb(1,c));

hforced(r,c)=hf1;

hfree(r,c)=hf2;

c = c + 1;

end

c = 1;

r = r + 1;

end

f = 1;

Qfree = 0;

while f <= 100

Tfilm = ((Thum + Tfree(1,f))/2); %film t in Kelvin

%interpolation k, dens, visc, and Pr

k = ((k300-k250)/(300-250))*(Tfilm-250)+k250;

dens = ((dens300-dens250)/(300-250))*(Tfilm-250)+dens250;

visc = ((visc300-visc250)/(300-250))*(Tfilm-250)+visc250;

Pr = ((Pr300-Pr250)/(300-250))*(Tfilm-250)+Pr250;

%q te forced

%q related to velocity and t

%to get free convection

Beta = 1/Tfilm;

Gr = (length^3*(Thum-Tamb(1,c))*(dens^2)*Beta*grav)/visc^2;

Ra = Gr*Pr;

if Ra >= 10^4 && Ra <= 10^9

cf2 = 0.59;

mf2 = 1/4;

else if Ra > 10^9 && Ra <= 10^13

cf2 = 0.1;

mf2 = 1/3;

end

end

Nuf = cf2*(Ra^(mf2));

%end

hf2 = (Nuf*k)/length;

hfree(1,f) = hf2;

%to get wind chill temp

Qfree = hf2 * (Thum-Tfree(1,f));

f = f + 1;

end

r = 1;

c = 1;

iterations = 1;

TwindChill = zeros(10);

while r <= 10

while c<= 10

while iterations <= 10000000

if abs(Qforced(r,c) - Qfree(1,iterations)) < 0.001 --> line 116

TwindChill(r,c) = Tfree(1,iterations) - 273;

else

TwindChill(r,c) = TwindChill(r,c);

end

iterations = iterations + 1;

end

iterations = 1;

c= c+1;

end

c=1;

r = r +1;

end

%output Twind hforced hfree

Twd;

hforced;

hfree;

%plot Twind, Tamb, Vwind

%plot3(Twind, Tamb, Vwind, 'r-');

%grid on;

%legend('Wind Chill') %change the file name

%xlabel('Wind Chill Temperature')

%ylabel('Ambient Temperature')

%zlabel('Wind Velocity')

%smooth lines

%hold on

Answer 1

[Asvin Kumar]

At some point in your program, either the ‘r’ or ‘c’ or ‘iterations’ variables are being used to index into a position in their respective matrices which does not exist. So, this might mean one or many of these things:

1. The value of ‘r’ is larger than the number of rows in ‘Qforced’. Use >> size(Qforced,1) to find the number of rows in ‘Qforced’.
2. The value of ‘c’ is larger than the number of columns in ‘Qforced’. Use >> size(Qforced,2) to find the number of columns in ‘Qforced’.
3. The value of ‘iterations’ is larger than the number of columns in ‘Qfree’. Use >> size(Qfree,2) to find the number of columns in ‘Qfree’.