vtb3_5.m

The Engineering Vibration Toolbox is a set of educational programs written in Octave by Joseph C.

function [ap,bp]=vtb3_5(a0,a,b,N,T)
%VTB3_5  Plot Fourier Series Approximation of Function.
%  VTB3_5(a0,a,b,N,T) Plot the Fourier series defined by:
%  N is the number of terms. Other arguments as defined by Inman
%  a and b should ideally be strings as shown in the example following
%
%  Example
%
%  vtb3_5(-1,0,'-3*(-1+(-1)^n)/n/pi',20,2)
%  %Plot a 20 term Fourier series representation of a shifted square wave
%  %High value should be 1, low value should be -2.
%



% Copyright Joseph C. Slater, Dec 2006

if nargin>0
    if ~ischar(a0)
        a0=num2str(a0);
    end

    if ~ischar(a)
        a=num2str(a);
    end

    if ~ischar(b)
        b=num2str(b);
    end

    if ischar(T)
        T=str2num(T);
    end

    if ischar(N)
        N=str2num(N);
    end



    t=0:T/400:T*3;
    F=0*t+eval(a0)/2;
    for n=1:N
        F=F+eval(a)*cos(n*2*pi*t/T)+eval(b)*sin(n*2*pi*t/T);
    end
   
    plot(t,F)
    grid on
  
else
    vtb3_5(-1,0,'-3*(-1+(-1)^n)/n/pi',20,2)
end