Eigen  3.3.0
 
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arch/ZVector/MathFunctions.h
1// This file is part of Eigen, a lightweight C++ template library
2// for linear algebra.
3//
4// Copyright (C) 2007 Julien Pommier
5// Copyright (C) 2009 Gael Guennebaud <gael.guennebaud@inria.fr>
6//
7// This Source Code Form is subject to the terms of the Mozilla
8// Public License v. 2.0. If a copy of the MPL was not distributed
9// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
10
11/* The sin, cos, exp, and log functions of this file come from
12 * Julien Pommier's sse math library: http://gruntthepeon.free.fr/ssemath/
13 */
14
15#ifndef EIGEN_MATH_FUNCTIONS_ALTIVEC_H
16#define EIGEN_MATH_FUNCTIONS_ALTIVEC_H
17
18namespace Eigen {
19
20namespace internal {
21
22template<> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED
23Packet2d pexp<Packet2d>(const Packet2d& _x)
24{
25 Packet2d x = _x;
26
27 _EIGEN_DECLARE_CONST_Packet2d(1 , 1.0);
28 _EIGEN_DECLARE_CONST_Packet2d(2 , 2.0);
29 _EIGEN_DECLARE_CONST_Packet2d(half, 0.5);
30
31 _EIGEN_DECLARE_CONST_Packet2d(exp_hi, 709.437);
32 _EIGEN_DECLARE_CONST_Packet2d(exp_lo, -709.436139303);
33
34 _EIGEN_DECLARE_CONST_Packet2d(cephes_LOG2EF, 1.4426950408889634073599);
35
36 _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_p0, 1.26177193074810590878e-4);
37 _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_p1, 3.02994407707441961300e-2);
38 _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_p2, 9.99999999999999999910e-1);
39
40 _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_q0, 3.00198505138664455042e-6);
41 _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_q1, 2.52448340349684104192e-3);
42 _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_q2, 2.27265548208155028766e-1);
43 _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_q3, 2.00000000000000000009e0);
44
45 _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_C1, 0.693145751953125);
46 _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_C2, 1.42860682030941723212e-6);
47
48 Packet2d tmp, fx;
49 Packet2l emm0;
50
51 // clamp x
52 x = pmax(pmin(x, p2d_exp_hi), p2d_exp_lo);
53 /* express exp(x) as exp(g + n*log(2)) */
54 fx = pmadd(p2d_cephes_LOG2EF, x, p2d_half);
55
56 fx = vec_floor(fx);
57
58 tmp = pmul(fx, p2d_cephes_exp_C1);
59 Packet2d z = pmul(fx, p2d_cephes_exp_C2);
60 x = psub(x, tmp);
61 x = psub(x, z);
62
63 Packet2d x2 = pmul(x,x);
64
65 Packet2d px = p2d_cephes_exp_p0;
66 px = pmadd(px, x2, p2d_cephes_exp_p1);
67 px = pmadd(px, x2, p2d_cephes_exp_p2);
68 px = pmul (px, x);
69
70 Packet2d qx = p2d_cephes_exp_q0;
71 qx = pmadd(qx, x2, p2d_cephes_exp_q1);
72 qx = pmadd(qx, x2, p2d_cephes_exp_q2);
73 qx = pmadd(qx, x2, p2d_cephes_exp_q3);
74
75 x = pdiv(px,psub(qx,px));
76 x = pmadd(p2d_2,x,p2d_1);
77
78 // build 2^n
79 emm0 = vec_ctsl(fx, 0);
80
81 static const Packet2l p2l_1023 = { 1023, 1023 };
82 static const Packet2ul p2ul_52 = { 52, 52 };
83
84 emm0 = emm0 + p2l_1023;
85 emm0 = emm0 << reinterpret_cast<Packet2l>(p2ul_52);
86
87 // Altivec's max & min operators just drop silent NaNs. Check NaNs in
88 // inputs and return them unmodified.
89 Packet2ul isnumber_mask = reinterpret_cast<Packet2ul>(vec_cmpeq(_x, _x));
90 return vec_sel(_x, pmax(pmul(x, reinterpret_cast<Packet2d>(emm0)), _x),
91 isnumber_mask);
92}
93
94template<> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED
95Packet2d psqrt<Packet2d>(const Packet2d& x)
96{
97 return __builtin_s390_vfsqdb(x);
98}
99
100template<> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED
101Packet2d prsqrt<Packet2d>(const Packet2d& x) {
102 // Unfortunately we can't use the much faster mm_rqsrt_pd since it only provides an approximation.
103 return pset1<Packet2d>(1.0) / psqrt<Packet2d>(x);
104}
105
106} // end namespace internal
107
108} // end namespace Eigen
109
110#endif // EIGEN_MATH_FUNCTIONS_ALTIVEC_H
Namespace containing all symbols from the Eigen library.
Definition: Core:287