how to integrate inside 'for' loop

2 views (last 30 days)
I am new to matlab. All i wanted was to integrate f(t)*cos(pi*n*t) over t through quadgk inside a loop where n varies from 1 to 10. But I guess the problem is that quadgk needs a function where only t is a variable and not n. how to do it???
t=linspace(0,12,1000);
T=2;
Y=g(t)';
rep=(t(end)-t([1]))/T;
f=0;
N=5;
hold on;
h=zeros(N,1);
clr=lines(N);
for n=1:2:N;
line(t,Y,'linewidth',5)
grid on;hold on;
A=(1/T)*quadgk(@g,0,T);
P=Y.*(cos(n*pi*t))';
Q=Y.*(sin(n*pi*t))';
Ax=(2/T)*quadgk(@s,0,T);
Bx=(2/T)*trapz(t,Q)/rep;
f=f+(Ax*cos(pi*n*t)+Bx*sin(pi*n*t));
final=A+f;
h(n)=plot(t,final,'linewidth',2,'Color',clr(n,:));
end
hold off;
legend(h, num2str((1:N)','harmonic-%d'))
function f=g(x)
z=2*floor(x/2);
x1=x-z;
y1=(1).*(0<=x1 & x1<=0.8);
y2=(-1).*(0.8<x1 & x1<2);
f=y1+y2;

Accepted Answer

Matz Johansson Bergström
Matz Johansson Bergström on 24 Aug 2014
Edited: Matz Johansson Bergström on 24 Aug 2014
To solve this problem you can use a anonymous function handle to a function with x and n as arguments.
f = @(x) myfun(x, n);
So you define your function with 'function myfun(x,n)' and pass the handle f to quadgk like
quadgk(f,0,T)
Please note that I don't use @ here.
  6 Comments
Nabhdeep Bansal
Nabhdeep Bansal on 24 Aug 2014
What you are saying is true Sir. The output curves are incorrect. How to pass n as an extra argument?
Matz Johansson Bergström
Matz Johansson Bergström on 24 Aug 2014
You want to calculate the quadrature of f(t)*cos(pi*n*t), how do you define f?

Sign in to comment.

More Answers (0)

Categories

Find more on Programming in Help Center and File Exchange

Products

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!