MatLab error when plotting function

Question

So I have to draw some graphs in MatLab.

At first I save this as a .m file:

function y = f(x)
y = sqrt((abs(sin(21*pi*x)))/(2+sin(20*pi*x)));

Then I do:

x=[0:0.05:1]
y=f(x)

and then when I need to draw the graph, using

plot(x,f)

I get this error:

??? Input argument "x" is undefined.
Error in ==> f at 2
y = sqrt((abs(sin(21*pi*x)))/(2+sin(20*pi*x)));

Can someone tell me what is the problem here?

bla · Accepted Answer · 2012-12-03 21:20:35Z

3

you need to have the ./ operator instead of / when dividing two vectors element by element. Try this instead

x = 0:0.05:1;
y = sqrt((abs(sin(21*pi*x)))./(2+sin(20*pi*x)));
plot(x,y)

enter image description here

answered Dec 3, 2012 at 21:08

bla

26.1k11 gold badges72 silver badges105 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

hm.. i still get the error but it draws at least, a triangle :)

sorry, typo of 0.5 instead of 0.05 in the x step. I've edited the answer, try again.