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Fix SSE plog<float> to return -INF on 0

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(transplanted from 8745da14d8609425764c399c6ac1f44235277ef3
)
This commit is contained in:
Gael Guennebaud 2013-02-14 23:34:05 +01:00
parent 66cbfd4d39
commit 6adc13ea04
2 changed files with 8 additions and 4 deletions
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10
Eigen/src/Core/arch/SSE/MathFunctions.h
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@ -31,7 +31,8 @@ Packet4f plog<Packet4f>(const Packet4f& _x)
/* the smallest non denormalized float number */
_EIGEN_DECLARE_CONST_Packet4f_FROM_INT(min_norm_pos, 0x00800000);
_EIGEN_DECLARE_CONST_Packet4f_FROM_INT(minus_inf, 0xff800000);//-1.f/0.f);
/* natural logarithm computed for 4 simultaneous float
return NaN for x <= 0
*/
@ -51,7 +52,8 @@ Packet4f plog<Packet4f>(const Packet4f& _x)
Packet4i emm0;
Packet4f invalid_mask = _mm_cmple_ps(x, _mm_setzero_ps());
Packet4f invalid_mask = _mm_cmplt_ps(x, _mm_setzero_ps());
Packet4f iszero_mask = _mm_cmpeq_ps(x, _mm_setzero_ps());
x = pmax(x, p4f_min_norm_pos); /* cut off denormalized stuff */
emm0 = _mm_srli_epi32(_mm_castps_si128(x), 23);
@ -96,7 +98,9 @@ Packet4f plog<Packet4f>(const Packet4f& _x)
y2 = pmul(e, p4f_cephes_log_q2);
x = padd(x, y);
x = padd(x, y2);
return _mm_or_ps(x, invalid_mask); // negative arg will be NAN
// negative arg will be NAN, 0 will be -INF
return _mm_or_ps(_mm_andnot_ps(iszero_mask, _mm_or_ps(x, invalid_mask)),
_mm_and_ps(iszero_mask, p4f_minus_inf));
}
template<> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED

2
test/packetmath.cpp
View File

@ -40,7 +40,7 @@ template<typename Scalar> bool areApprox(const Scalar* a, const Scalar* b, int s
{
for (int i=0; i<size; ++i)
{
if (!internal::isApprox(a[i],b[i]))
if (a[i]!=b[i] && !internal::isApprox(a[i],b[i]))
{
std::cout << "[" << Map<const Matrix<Scalar,1,Dynamic> >(a,size) << "]" << " != " << Map<const Matrix<Scalar,1,Dynamic> >(b,size) << "\n";
return false;