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Fix pdiv for complex packets involving infinites.

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libeigen/eigen!2131
This commit is contained in:
Antonio Sánchez
2026-02-15 01:47:32 +00:00
committed by Rasmus Munk Larsen
parent 9b709e8269
commit 1a2b80727c
4 changed files with 89 additions and 69 deletions
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23
Eigen/src/Core/arch/Default/GenericPacketMathFunctions.h
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@@ -1553,21 +1553,20 @@ EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS Packet patanh_double(const P
template <typename Packet>
EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS Packet pdiv_complex(const Packet& x, const Packet& y) {
typedef typename unpacket_traits<Packet>::as_real RealPacket;
typedef typename unpacket_traits<RealPacket>::type RealScalar;
// In the following we annotate the code for the case where the inputs
// are a pair length-2 SIMD vectors representing a single pair of complex
// numbers x = a + i*b, y = c + i*d.
const RealPacket y_abs = pabs(y.v); // |c|, |d|
const RealPacket y_abs_flip = pcplxflip(Packet(y_abs)).v; // |d|, |c|
const RealPacket y_max = pmax(y_abs, y_abs_flip); // max(|c|, |d|), max(|c|, |d|)
const RealPacket y_scaled = pdiv(y.v, y_max); // c / max(|c|, |d|), d / max(|c|, |d|)
// Compute scaled denominator.
const RealPacket y_scaled_sq = pmul(y_scaled, y_scaled); // c'**2, d'**2
const RealPacket denom = padd(y_scaled_sq, pcplxflip(Packet(y_scaled_sq)).v);
Packet result_scaled = pmul(x, pconj(Packet(y_scaled))); // a * c' + b * d', -a * d + b * c
// Divide elementwise by denom.
result_scaled = Packet(pdiv(result_scaled.v, denom));
// Rescale result
return Packet(pdiv(result_scaled.v, y_max));
static const RealPacket one = pset1<RealPacket>(RealScalar(1));
const RealPacket y_flip = pcplxflip(y).v;
// We need to avoid dividing by Inf/Inf, so use a mask to carefully
// apply the scale.
const RealPacket mask = pcmp_lt(pabs(y.v), pabs(y_flip)); // |c| < |d|
const RealPacket y_scaled = pselect(mask, pdiv(y.v, y_flip), one);
RealPacket denom = pmul(y.v, y_scaled);
denom = padd(denom, pcplxflip(Packet(denom)).v); // c * c' + d * d'
Packet num = pmul(x, pconj(Packet(y_scaled))); // a * c' + b * d', -a * d + b * c
return Packet(pdiv(num.v, denom));
}
template <typename Packet>