Plotting values from a function in different script

function [xvals,yvals]=fourier(L,nmax,numpoints)
xvals=[];
yvals=[];
for x=1:numpoints
    y=0;
    for n=1:2:nmax
        y=y+(1/n)*(sin((n*pi*x)/L));
    end
    y=4*y/pi;
    xvals=[xvals;x];
    yvals=[yvals;y];
end
end
====================================================
[xvals,yvals]=fourier(L,nmax,numpoints);

x = xvals;
y = yvals; 

L= 0;

plot(x, y);

I have a function that returns two very long column vectors for xvals and yvals. I'm struggling to create another script that calls upon this function and plots the respective xvals vs yvals. The code below the line gives me an error saying L is not recognized but I don't use it so I'm a bit confused.

Answer 1

[KSSV]

You have to define the required input variables first and then call the function.

L = 1. ;
nmax = 100 ;
numpoints = 1000 ;
[x,y]=fourier(L,nmax,numpoints);
plot(x,y);

function [xvals,yvals]=fourier(L,nmax,numpoints)
xvals=zeros(numpoints,1) ;
yvals=zeros(numpoints,1) ;
for i=1:numpoints
    y=0;
    for n=1:2:nmax
        y=y+(1/n)*(sin((n*pi*i)/L));
    end
    y=4*y/pi;
    yvals(i) = y ; 
    xvals(i) = i ;     
end
end

[Sarah Gomez]

I'm not sure why this solution returns a very strange graph. I'm hoping for the textbook square wave of my fourier series.

[KSSV]

It depends on the input you have given. Show us your input.

You might be inputting L as zero? Is it... If so change L, L cannot be zero, As it comes in the denominator, all your y values will be zero.

I have edited the code.

[Sarah Gomez]

I've tried returning a sign wave for random inputs but I can't get it right.

[xvals, yvals] = fourier(0.1, 3, 200)

[xvals, yvals] = fourier(0.1, 9, 200)

[xvals, yvals] = fourier(0.1, 100, 200)

They all return fine but not in the shape I want.

For example the top tests returns a graph like this