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Factorize the 4 copies of tanh implementations, make numext::tanh consistent with array::tanh, enable fast tanh in fast-math mode only.

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This commit is contained in:
Gael Guennebaud
2016-08-23 14:23:08 +02:00
parent 82147cefff
commit a4c266f827
6 changed files with 89 additions and 193 deletions
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108
Eigen/src/Core/functors/UnaryFunctors.h
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@@ -498,113 +498,11 @@ struct functor_traits<scalar_atan_op<Scalar> >
template <typename Scalar>
struct scalar_tanh_op {
EIGEN_EMPTY_STRUCT_CTOR(scalar_tanh_op)
EIGEN_DEVICE_FUNC inline const Scalar operator()(const Scalar& a) const {
/** \internal \returns the hyperbolic tan of \a a (coeff-wise)
Doesn't do anything fancy, just a 13/6-degree rational interpolant
which
is accurate up to a couple of ulp in the range [-9, 9], outside of
which
the fl(tanh(x)) = +/-1. */
// Clamp the inputs to the range [-9, 9] since anything outside
// this range is +/-1.0f in single-precision.
const Scalar plus_9 = static_cast<Scalar>(9.0);
const Scalar minus_9 = static_cast<Scalar>(-9.0);
const Scalar x = numext::maxi(minus_9, numext::mini(plus_9, a));
// Scalarhe monomial coefficients of the numerator polynomial (odd).
const Scalar alpha_1 = static_cast<Scalar>(4.89352455891786e-03);
const Scalar alpha_3 = static_cast<Scalar>(6.37261928875436e-04);
const Scalar alpha_5 = static_cast<Scalar>(1.48572235717979e-05);
const Scalar alpha_7 = static_cast<Scalar>(5.12229709037114e-08);
const Scalar alpha_9 = static_cast<Scalar>(-8.60467152213735e-11);
const Scalar alpha_11 = static_cast<Scalar>(2.00018790482477e-13);
const Scalar alpha_13 = static_cast<Scalar>(-2.76076847742355e-16);
// Scalarhe monomial coefficients of the denominator polynomial (even).
const Scalar beta_0 = static_cast<Scalar>(4.89352518554385e-03);
const Scalar beta_2 = static_cast<Scalar>(2.26843463243900e-03);
const Scalar beta_4 = static_cast<Scalar>(1.18534705686654e-04);
const Scalar beta_6 = static_cast<Scalar>(1.19825839466702e-06);
// Since the polynomials are odd/even, we need x^2.
const Scalar x2 = x * x;
// Evaluate the numerator polynomial p.
Scalar p = x2 * alpha_13 + alpha_11;
p = x2 * p + alpha_9;
p = x2 * p + alpha_7;
p = x2 * p + alpha_5;
p = x2 * p + alpha_3;
p = x2 * p + alpha_1;
p = x * p;
// Evaluate the denominator polynomial p.
Scalar q = x2 * beta_6 + beta_4;
q = x2 * q + beta_2;
q = x2 * q + beta_0;
// Divide the numerator by the denominator.
return p / q;
}
EIGEN_DEVICE_FUNC inline const Scalar operator()(const Scalar& a) const { return numext::tanh(a); }
template <typename Packet>
EIGEN_DEVICE_FUNC inline Packet packetOp(const Packet& _x) const {
/** \internal \returns the hyperbolic tan of \a a (coeff-wise)
Doesn't do anything fancy, just a 13/6-degree rational interpolant which
is accurate up to a couple of ulp in the range [-9, 9], outside of which
the
fl(tanh(x)) = +/-1. */
// Clamp the inputs to the range [-9, 9] since anything outside
// this range is +/-1.0f in single-precision.
const Packet plus_9 = pset1<Packet>(9.0);
const Packet minus_9 = pset1<Packet>(-9.0);
const Packet x = pmax(minus_9, pmin(plus_9, _x));
// The monomial coefficients of the numerator polynomial (odd).
const Packet alpha_1 = pset1<Packet>(4.89352455891786e-03);
const Packet alpha_3 = pset1<Packet>(6.37261928875436e-04);
const Packet alpha_5 = pset1<Packet>(1.48572235717979e-05);
const Packet alpha_7 = pset1<Packet>(5.12229709037114e-08);
const Packet alpha_9 = pset1<Packet>(-8.60467152213735e-11);
const Packet alpha_11 = pset1<Packet>(2.00018790482477e-13);
const Packet alpha_13 = pset1<Packet>(-2.76076847742355e-16);
// The monomial coefficients of the denominator polynomial (even).
const Packet beta_0 = pset1<Packet>(4.89352518554385e-03);
const Packet beta_2 = pset1<Packet>(2.26843463243900e-03);
const Packet beta_4 = pset1<Packet>(1.18534705686654e-04);
const Packet beta_6 = pset1<Packet>(1.19825839466702e-06);
// Since the polynomials are odd/even, we need x^2.
const Packet x2 = pmul(x, x);
// Evaluate the numerator polynomial p.
Packet p = pmadd(x2, alpha_13, alpha_11);
p = pmadd(x2, p, alpha_9);
p = pmadd(x2, p, alpha_7);
p = pmadd(x2, p, alpha_5);
p = pmadd(x2, p, alpha_3);
p = pmadd(x2, p, alpha_1);
p = pmul(x, p);
// Evaluate the denominator polynomial p.
Packet q = pmadd(x2, beta_6, beta_4);
q = pmadd(x2, q, beta_2);
q = pmadd(x2, q, beta_0);
// Divide the numerator by the denominator.
return pdiv(p, q);
}
};
template <>
struct scalar_tanh_op<std::complex<double> > {
EIGEN_DEVICE_FUNC inline const std::complex<double> operator()(
const std::complex<double>& a) const {
return numext::tanh(a);
}
};
template <>
struct scalar_tanh_op<std::complex<float> > {
EIGEN_DEVICE_FUNC inline const std::complex<float> operator()(
const std::complex<float>& a) const {
return numext::tanh(a);
}
EIGEN_DEVICE_FUNC inline Packet packetOp(const Packet& x) const { return ptanh(x); }
};
template <typename Scalar>
struct functor_traits<scalar_tanh_op<Scalar> > {
enum {