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ei_psqrt fix for zero input

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This commit is contained in:
Hauke Heibel 2010-04-01 15:10:52 +02:00
parent 1b3f7f2fee
commit 9d6afdeb22
1 changed files with 8 additions and 4 deletions
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12
Eigen/src/Core/arch/SSE/MathFunctions.h
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@ -369,10 +369,14 @@ static EIGEN_DONT_INLINE EIGEN_UNUSED Packet4f ei_pcos(Packet4f x)
// For detail see here: http://www.beyond3d.com/content/articles/8/
static EIGEN_UNUSED Packet4f ei_psqrt(Packet4f _x)
{
Packet4f half = ei_pmul(_x, ei_pset1(.5f));
Packet4f x = _mm_rsqrt_ps(_x);
x = ei_pmul(x, ei_psub(ei_pset1(1.5f), ei_pmul(half, ei_pmul(x,x))));
return ei_pmul(_x,x);
Packet4f half = ei_pmul(_x, ei_pset1(.5f));
/* select only the inverse sqrt of non-zero inputs */
Packet4f non_zero_mask = _mm_cmpgt_ps(_x, ei_pset1(std::numeric_limits<float>::epsilon()));
Packet4f x = _mm_and_ps(non_zero_mask, _mm_rsqrt_ps(_x));
x = ei_pmul(x, ei_psub(ei_pset1(1.5f), ei_pmul(half, ei_pmul(x,x))));
return ei_pmul(_x,x);
}
#endif // EIGEN_MATH_FUNCTIONS_SSE_H