2010/1/30 Daniel Russel <>:
> Check that the choice of Euler angles isn't singular near that point (each
> choice of Euler angles has a place where it is singular, meaning very
> different Euler angle values produce almost the same rotation).
Yes, I think that is what is happening here, but I don't know how to repair it.
How does the
> instability manifest itself.
When psi is 0, then sin(psi) = 0 and you're dividing by it. Needs a
check, that is what I did. Does it help?
>
> I'll try to look more into it later.
>
>
> On Jan 29, 2010, at 8:46 PM, Javier Ángel Velázquez Muriel
> <> wrote:
>
>> That function enters into numerical instability when
>> sin_tilt_sin_psi==0, which produces psi ==0. I've tried to fixe it,
>> and i think is correct, but now the code throws the exception. The
>> input and output are "apart". Can anybody help me to fix it? Anything
>> that I missed?
>>
>> double psi= std::atan2(sin_tilt_sin_psi, cos_psi_sin_tilt);
>> if(almost_equal(sin_tilt_sin_psi,0,1e-6)) {
>> double sin_tilt= 0;
>> double tilt= std::atan2(sin_tilt, cos_tilt);
>> } else {
>> double sin_tilt= sin_tilt_sin_psi/std::sin(psi);
>> double tilt= std::atan2(sin_tilt, cos_tilt);
>> }
>> // double cos_rot= cos_rot_sin_tilt/sin_tilt;
>> // double sin_rot= sin_rot_sin_tilt/sin_tilt;
>> // double rot= std::atan2(sin_rot, cos_rot);
>> double rot= std::atan2(sin_rot, cos_rot);
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