Re: [eigen] Transform.rotation() hang

[Keir Mierle <mierle@xxxxxxxxx>]

I suspect a .truncate() function would be generally useful.

Matrix.... M;
M.truncate()
M.clampSmallValues()
M.truncateNegligible()
M..?  Other ideas?

Keir

On Tue, Feb 10, 2009 at 1:01 PM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote:

Meanwhile, here are some thoughts if you absolutely have to live with
the current SVD.

What I can see on your matrices, is that while their norm is (of the
order of magnitude of) 1, they have some coefficients of the order of
magnitude of 1e-300. That could easily be what triggers a bug in the
current SVD.

So one thing you can do, before calling the SVD (i.e. before calling
rotation()) is to:
1) compute N = matrix.norm()
2) for each entry matrix(i,j),
 if(ei_isMuchSmallerThan(matrix(i,j), N))
   matrix(i,j) = 0;

Cheers,
Benoit

2009/2/10 Ben Axelrod <baxelrod@xxxxxxxxxxxx>:

> Sometimes calling Eigen::Transform.rotation() hangs and does not return.
>
>
>
> This transform matrix runs fine:
>
> 1            0   -1.931e-312  1
>
> 0            1    0           0
>
> 1.931e-312   0    1           1.5
>
> 0            0    0           1
>
>
>
> This transform matrix hangs:
>
> 1            0   -2.357e-312  1
>
> 0            1    0           0
>
> 1.179e-311   0    5           7.5
>
> 0            0    0           1
>
>
>
>
>
> Any help?
>
>
>
> Detailed info: the transforms were computed by:
>
>
>
> Tf * Tr * Qt * Sc
>
>
>
> Where, for the good transform:
>
>
>
> Tf = Transform:
>
> 1 0 0 1
>
> 0 1 0 0
>
> 0 0 1 0
>
> 0 0 0 1
>
>
>
> Tr = Translation:
>
> 0
>
> 0
>
> 1.5
>
>
>
> Qt = Quaternion:
>
> 0
>
> -9.653e-313
>
> 0
>
> 1
>
>
>
> Sc = Scaling:
>
> 1
>
> 1
>
> 1
>
>
>
>
>
> And for the bad transform:
>
>
>
> Tf = Transform:
>
> 1 0 0 1
>
> 0 1 0 0
>
> 0 0 5 0
>
> 0 0 0 1
>
>
>
> Tr = Translation:
>
> 0
>
> 0
>
> 1.5
>
>
>
> Qt = Quaternion:
>
> 0
>
> -1.179e-312
>
> 0
>
> 1
>
>
>
> Sc = Scaling:
>
> 1
>
> 1
>
> 1
>
>
>
>
>
> Thanks,
>
> -Ben