Can't define functions in Matlab

Hello everyone, I have version R2012a of matlab and I would like to define this function to create direccional fields on first order differential equations. I created a notepad file with this code on it and exchanged the extension from .txt to .m and placed it on MATLAB/R2012a but it doesnt work. What am I doing wrong? Is it the folder? I also tried to put the code directily on matlab and run it but it failed.

function dirfield(f,tval,yval)
[tm,ym]=meshgrid(tval,yval);
dt = tval(2) - tval(1); 
dy = yval(2) - yval(1);
yp=feval(vectorize(f),tm,ym); 
s = 1./max(1/dt,abs(yp)./dy)*0.35;
h = ishold;
quiver(tval,yval,s,s.*yp,0,'.r'); hold on;
quiver(tval,yval,-s,-s.*yp,0,'.r');
if h
hold on
else
hold off
end

axis([tval(1)-dt/2,tval(end)+dt/2,yval(1)-dy/2,yval(end)+dy/2])

I would apreciate your help!

[Jan]

What does "placed it on MATLAB/R2012a" exactly mean?

Answer 1

[Matt Fig]

At the command prompt, type: edit

Now paste your code into the window that opens up. Then save it. From the commamd prompt use the same name as you saved the file.

Answer 2

[Elizabeth]

Your function name must match the file name you save it under. Could this be the issue?

Answer 3

[Pedro]

Thanks, I did what you said and it saved it on MATLAB/R2012a/bin , it had to be there. By the way, do these programs work on mathematica too?