Plotting error message

Hi,

I am running this code:

y1 = 0:.01:1;

for y2=0:1/10:1;

l=1+y2*10;

t(:,l) = y1.^3./12 + (y1.^2.*y2)/4 - y1.^2./2 + (y1.*y2.^2)/4 - y1.*y2 + y1 
- (7.*y2.^3)/12 + (3.*y2.^2)/2 - y2;

end

plot(y1,t)

and get this error:

Subscript indices must either be real positive integers or logicals.

However when I run this code:

y1 = 0:.01:1;

for y2=0:1/10:0.5;

l=1+y2*10;

t(:,l) = y1.^3./12 + (y1.^2.*y2)/4 - y1.^2./2 + (y1.*y2.^2)/4 - y1.*y2 + y1 
- (7.*y2.^3)/12 + (3.*y2.^2)/2 - y2;

end

plot(y1,t)

There is no problem! (only difference is the 3rd line)

Can someone explain why I cannot do the first one?

Best,

David

Answer 1

[Wayne King]

You have the line:

 l=1+y2*10;

and then you try to use that to index the columns of t(), but you actually have an index not equal to an integer

l =

   7.000000000000001

I'm not sure why you're trying to do here, but how about

   l=1+round(y2*10);

That should enable your loop to run and produce your plot.

Answer 2

[Walter Roberson]

http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F

Answer 3

[old_user_rat]

Thanks guys, that's clear now