Prev: Vectorisation With Indefinite Indices
Next: mean of quantized image
From: Laurens on 5 Aug 2010 06:09
Hi,

I'm trying to make a Matlab movie of a function I wrote, using the spy command.

The problem is that some elements that should be zero in the matrix I want to plot, are actually -0.0000 (or 0.0000), probably due to rounding errors. How do I make sure these will actually be 0?

I tried rounding every element that I expect to be 0 with the round function, but this seems to me a very inefficient and dirty way. Isn't there a more elegant way to make sure these elements that are "almost zero" don't occur? They screw up the frames generated by the spy command.

Thanks.
From: Neil Stewart on 5 Aug 2010 06:25
"Laurens " <laurens.vankeer(a)student.kuleuven.be> wrote in message <i3e2k1$ce9$1(a)fred.mathworks.com>...
> Hi,
>
> I'm trying to make a Matlab movie of a function I wrote, using the spy command.
>
> The problem is that some elements that should be zero in the matrix I want to plot, are actually -0.0000 (or 0.0000), probably due to rounding errors. How do I make sure these will actually be 0?
>
> I tried rounding every element that I expect to be 0 with the round function, but this seems to me a very inefficient and dirty way. Isn't there a more elegant way to make sure these elements that are "almost zero" don't occur? They screw up the frames generated by the spy command.
>
> Thanks.

Hi,

I'm not familiar with the spy command so I'm not sure if I can be of much use to you.

Maybe you could implement a tolerance threshold?
Var(Var<0.000001 | Var>-0.000001)=0

Neil
From: Laurens on 5 Aug 2010 07:50
Hi Neil,

I think you meant Var(Var<0.000001 & Var>-0.000001)=0, instead of the "or" (otherwise all elements will be 0), and that seems to work! Thanks!
From: Neil Stewart on 5 Aug 2010 07:56
"Laurens " <laurens.vankeer(a)student.remove.this.kuleuven.be> wrote in message <i3e8hh$pd9$1(a)fred.mathworks.com>...
> Hi Neil,
>
> I think you meant Var(Var<0.000001 & Var>-0.000001)=0, instead of the "or" (otherwise all elements will be 0), and that seems to work! Thanks!

Yeah, my bad!

Glad I could help.
 | 
Pages: 1
Prev: Vectorisation With Indefinite Indices
Next: mean of quantized image