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Make sure that psin/pcos return number in [-1,1] for large inputs (though sin/cos on large entries is quite useless because it's inaccurate)

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This commit is contained in:
Gael Guennebaud 2018-12-23 16:13:24 +01:00
parent 5713fb7feb
commit 38d704def8
2 changed files with 22 additions and 0 deletions
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6
Eigen/src/Core/arch/Default/GenericPacketMathFunctions.h
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@ -289,9 +289,15 @@ Packet psincos_float(const Packet& _x)
const Packet cst_coscof_p1 = pset1<Packet>(-1.388731625493765E-003f);
const Packet cst_coscof_p2 = pset1<Packet>( 4.166664568298827E-002f);
const Packet cst_cephes_FOPI = pset1<Packet>( 1.27323954473516f); // 4 / M_PI
const Packet cst_sincos_max_arg = pset1<Packet>( 13176795.0f); // Approx. (2**24) / (4/Pi).
Packet x = pabs(_x);
// Prevent sin/cos from generating values larger than 1.0 in magnitude
// for very large arguments by setting x to 0.0.
Packet small_or_nan_mask = pcmp_lt_or_nan(x, cst_sincos_max_arg);
x = pand(x, small_or_nan_mask);
// Scale x by 4/Pi to find x's octant.
Packet y = pmul(x, cst_cephes_FOPI);

16
test/packetmath.cpp
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@ -564,6 +564,22 @@ template<typename Scalar,typename Packet> void packetmath_real()
VERIFY((numext::isnan)(data2[0]));
VERIFY((numext::isnan)(data2[1]));
}
if(PacketTraits::HasCos)
{
packet_helper<PacketTraits::HasCos,Packet> h;
for(Scalar k = 1; k<Scalar(1000)/std::numeric_limits<Scalar>::epsilon(); k*=2) {
data1[0] = k*Scalar(EIGEN_PI) * internal::random<Scalar>(0.8,1.2);
data1[1] = (k+1)*Scalar(EIGEN_PI) * internal::random<Scalar>(0.8,1.2);
h.store(data2, internal::pcos(h.load(data1)));
VERIFY(data2[0]<=Scalar(1.) && data2[0]>=Scalar(-1.));
VERIFY(data2[1]<=Scalar(1.) && data2[1]>=Scalar(-1.));
data1[0] = (2*k+1)*Scalar(EIGEN_PI)/2 * internal::random<Scalar>(0.8,1.2);
data1[1] = (2*k+3)*Scalar(EIGEN_PI)/2 * internal::random<Scalar>(0.8,1.2);
h.store(data2, internal::psin(h.load(data1)));
VERIFY(data2[0]<=Scalar(1.) && data2[0]>=Scalar(-1.));
VERIFY(data2[1]<=Scalar(1.) && data2[1]>=Scalar(-1.));
}
}
}
}