can't do this

can't do this

Hi, I'm attempting nested for loops and failing miserably.

Here's my code: -

close all; 
clear all;
l=50;R=100;T=68;m=0.000125;w0=0.1;t=0;
mu=m/l;c=T/mu;
r=2;x0=l/r;
iter=1;
for x=1:33;
    iter=1;
        for n=1:5000;
        wxt=((4*w0)/pi)*exp(-R*t)*((l/(pi*n^2*x0))*sin((n*pi*x0)/l)-(1/n)*cos((n*pi*x0)/l)+(l/(2*n*x0))*cos((n*pi*x0)/l))*sin((n*pi*x)/l)*cos((c*n*pi*t)/l);
        wxtrec(iter)=wxt;
        iter=iter+1;
        end
    w=sum(wxtrec)
    wrec(iter)=w;
    iter=iter+1;
end
plot(x,wrec)

For the first outer loop run (x=1), I want the inner loop to do 5000 circuits, then I want the sum of that result. Then I want it to go around again 5000 times for x=2, taking a sum of that result etc.

Once I have 33 summed results, I want to plot those sums against x

[Image Analyst]

Next time, could you pick a more meaningful subject line than "can't do this"?

Answer 1

[Walter Roberson]

With minimal changes. Improvements are possible.

close all; 
clear all;
l=50;R=100;T=68;m=0.000125;w0=0.1;t=0;
mu=m/l;c=T/mu;
r=2;x0=l/r;
iter=1;
for x=1:33;
    iter=1;
        for n=1:5000;
        wxt=((4*w0)/pi)*exp(-R*t)*((l/(pi*n^2*x0))*sin((n*pi*x0)/l)-(1/n)*cos((n*pi*x0)/l)+(l/(2*n*x0))*cos((n*pi*x0)/l))*sin((n*pi*x)/l)*cos((c*n*pi*t)/l);
        %wxtrec(iter)=wxt;
        wxtrec(n)=wxt;  %NEW
        iter=iter+1;
        end
    w=sum(wxtrec)
    %wrec(iter)=w;
    wrec(x)=w;  %NEW AND IMPROVED
    iter=iter+1;
end
plot(x,wrec)

[Tom]

Hi thanks for answering. The code returns a message about subscript indices having to be either real positive integers or logicals. Should I be changing something?

[Walter Roberson]

Sorry, I had a typo which I have now corrected.