# To find integral of a function in loop

2 views (last 30 days)
Nadia jabeen on 6 Jul 2021
Commented: Alan Stevens on 6 Jul 2021
Hi,
I am calculating integral of a function 'f' with respect to lamda. I want to calculate variable 'q' for all possible values given in range of variable 'x'. upper limit and lower limit of variable lamda is as same as in variable 'x'. But matlab function given an error. kingly ghide me. or matlab show output of a single value. I want to do these calculations as a vector.
x = [600*10^-9:5*10^-9:800*10^-9];
for i = 1:numel(x)
N=(15.*z.*T*((h.*c).^3));
f=@(lamda)((Pi.^4).*(lamda.^4)*(k.^3));
q = integral(f,6e-7, x);
F=(N./q);
end

Alan Stevens on 6 Jul 2021
Try replacing
q = integral(f,6e-7, x);
with
q(i) = integral(f,6e-7, x(i));
##### 2 CommentsShowHide 1 older comment
Alan Stevens on 6 Jul 2021
q holds all the results! For example:
x = [600*10^-9:5*10^-9:800*10^-9];
% Arbitrary data - replace with your own
N=1; %(15.*z.*T*((h.*c).^3));
k = 10^3;
lambda = 10^4;
f=@(lamda)((pi.^4).*(lamda.^4)*(k.^3));
for i = 1:numel(x)
q(i) = integral(f,6e-7, x(i));
F=(N./q);
end
plot(x,q),grid
xlabel('x'),ylabel('q')