diff options
Diffstat (limited to 'Eigen/src/Core/arch/AVX/MathFunctions.h')
-rw-r--r-- | Eigen/src/Core/arch/AVX/MathFunctions.h | 42 |
1 files changed, 19 insertions, 23 deletions
diff --git a/Eigen/src/Core/arch/AVX/MathFunctions.h b/Eigen/src/Core/arch/AVX/MathFunctions.h index a24bf6e26..98d8e029f 100644 --- a/Eigen/src/Core/arch/AVX/MathFunctions.h +++ b/Eigen/src/Core/arch/AVX/MathFunctions.h @@ -267,31 +267,34 @@ pexp<Packet8f>(const Packet8f& _x) { // Hyperbolic Tangent function. // Doesn't do anything fancy, just a 13/6-degree rational interpolant which -// is accurate up to a couple of ulp in the range [-8, 8], outside of which the +// is accurate up to a couple of ulp in the range [-9, 9], outside of which the // fl(tanh(x)) = +/-1. template <> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED Packet8f ptanh<Packet8f>(const Packet8f& _x) { - // Map the range [-8, 8] to [-1, 1], we will clamp bad coefficients later. - const Packet8f x = _mm256_mul_ps(_x, _mm256_set1_ps(0.125f)); + // Clamp the inputs to the range [-9, 9] since anything outside + // this range is +/-1.0f in single-precision. + _EIGEN_DECLARE_CONST_Packet8f(plus_9, 9.0f); + _EIGEN_DECLARE_CONST_Packet8f(minus_9, -9.0f); + const Packet8f x = pmax(p8f_minus_9, pmin(p8f_plus_9, _x)); // The monomial coefficients of the numerator polynomial (odd). - _EIGEN_DECLARE_CONST_Packet8f(alpha_1, -2.47030171958948e-03f); - _EIGEN_DECLARE_CONST_Packet8f(alpha_3, -2.06804010015822e-02f); - _EIGEN_DECLARE_CONST_Packet8f(alpha_5, -3.13693994587418e-02f); - _EIGEN_DECLARE_CONST_Packet8f(alpha_7, -7.19851201683627e-03f); - _EIGEN_DECLARE_CONST_Packet8f(alpha_9, 8.31561269687160e-04f); - _EIGEN_DECLARE_CONST_Packet8f(alpha_11, -1.37626659546502e-04f); - _EIGEN_DECLARE_CONST_Packet8f(alpha_13, 1.39116714700458e-05f); + _EIGEN_DECLARE_CONST_Packet8f(alpha_1, 4.89352455891786e-03f); + _EIGEN_DECLARE_CONST_Packet8f(alpha_3, 6.37261928875436e-04f); + _EIGEN_DECLARE_CONST_Packet8f(alpha_5, 1.48572235717979e-05f); + _EIGEN_DECLARE_CONST_Packet8f(alpha_7, 5.12229709037114e-08f); + _EIGEN_DECLARE_CONST_Packet8f(alpha_9, -8.60467152213735e-11f); + _EIGEN_DECLARE_CONST_Packet8f(alpha_11, 2.00018790482477e-13f); + _EIGEN_DECLARE_CONST_Packet8f(alpha_13, -2.76076847742355e-16f); // The monomial coefficients of the denominator polynomial (even). - _EIGEN_DECLARE_CONST_Packet8f(beta_0, -3.08787724141615e-04f); - _EIGEN_DECLARE_CONST_Packet8f(beta_2, -9.17251911622436e-03f); - _EIGEN_DECLARE_CONST_Packet8f(beta_4, -3.09625062090444e-02f); - _EIGEN_DECLARE_CONST_Packet8f(beta_6, -2.05669680763032e-02f); + _EIGEN_DECLARE_CONST_Packet8f(beta_0, 4.89352518554385e-03f); + _EIGEN_DECLARE_CONST_Packet8f(beta_2, 2.26843463243900e-03f); + _EIGEN_DECLARE_CONST_Packet8f(beta_4, 1.18534705686654e-04f); + _EIGEN_DECLARE_CONST_Packet8f(beta_6, 1.19825839466702e-06f); // Since the polynomials are odd/even, we need x^2. - const Packet8f x2 = _mm256_mul_ps(x, x); + const Packet8f x2 = pmul(x, x); // Evaluate the numerator polynomial p. Packet8f p = pmadd(x2, p8f_alpha_13, p8f_alpha_11); @@ -308,14 +311,7 @@ ptanh<Packet8f>(const Packet8f& _x) { q = pmadd(x2, q, p8f_beta_0); // Divide the numerator by the denominator. - const Packet8f res = pdiv(p, q); - - // Mask-out values outside of [-8, 8]. - _EIGEN_DECLARE_CONST_Packet8f(one, 1.0f); - _EIGEN_DECLARE_CONST_Packet8f(minus_one, -1.0f); - return _mm256_blendv_ps( - _mm256_blendv_ps(res, p8f_one, _mm256_cmp_ps(x, p8f_one, _CMP_GT_OQ)), - p8f_minus_one, _mm256_cmp_ps(x, p8f_minus_one, _CMP_LT_OQ)); + return pdiv(p, q); } template <> |