Hello,

I'm quite a matlab dummy and it would be nice, if you could help me with this.

When integrating the following function I get the error "Array indices must be positive integers or logical values.". I think it's about the "f(x)-u_equ(x))" term, which is negative. But as the formula is like this I don't know what to do. Sorry in advance if the question/solution is trivial.

`clear all;n=1;t1 = 14;t2 = 25;len = 20; %length of model`

initemp = 10; %initial temperature

steps = 20;u_equ=zeros(1,steps);f=zeros(1,steps);% equilibrium temperature

for x=1:steps u_equ(x) = t1+((t2-t1)/len).*x; f(x) = initemp;endfun = @(x) (f(x)-u_equ(x)).*sin((n.*pi.*x)/len); %function to integrate

intgr = integral(fun,0,len)

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