fseries2.m

Communition MATLAB (Proakis)书的源程序

function xx=fseries(funfcn,a,b,n,tol,p1,p2,p3)
%FSERIES  	Returns the Fourier series coefficients.
%		XX=FSERIES(FUNFCN,A,B,N,TOL,P1,P2,P3)
%		funfcn=The given function, in an m-file.
%		It can depend on up to three parameters
%		p1,p2, and p3. The function is given
%		over one period extending from 'a' to 'b'
%		xx=vector of length n+1 of Fourier Series
%		Coefficients, xx0,xx1,...,xxn.
%		p1,p2,p3=parameters of funfcn. 
%		tol=the error level.

j=sqrt(-1);
args0=[];
for nn=1:nargin-5
  args=[args0,',p',int2str(nn)];
end
args=[args0,')'];
t=b-a;
xx(1)=eval(['1/(',num2str(t),').*quad(funfcn,a,b,tol,[]',args]);
for i=1:n
  newfun=['exp(-j*2*pi*x*(',int2str(i),')/(',num2str(t),'))'];
  xx(i+1)=eval(['1/(',num2str(t),').*quad(newfun,a,b,tol,newfun',args]);
end