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Consider denormals as zero in makeJacobi and 2x2 SVD.

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This also fix serious issues with x387 for which values can be much smaller than the smallest denormal!
This commit is contained in:
Gael Guennebaud 2016-07-12 17:21:03 +02:00
parent 263993a7b6
commit e2aa58b631
2 changed files with 5 additions and 3 deletions
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5
Eigen/src/Jacobi/Jacobi.h
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@ -85,7 +85,8 @@ bool JacobiRotation<Scalar>::makeJacobi(const RealScalar& x, const Scalar& y, co
using std::sqrt;
using std::abs;
typedef typename NumTraits<Scalar>::Real RealScalar;
if(y == Scalar(0))
RealScalar deno = RealScalar(2)*abs(y);
if(deno < (std::numeric_limits<RealScalar>::min)())
{
m_c = Scalar(1);
m_s = Scalar(0);
@ -93,7 +94,7 @@ bool JacobiRotation<Scalar>::makeJacobi(const RealScalar& x, const Scalar& y, co
}
else
{
RealScalar tau = (x-z)/(RealScalar(2)*abs(y));
RealScalar tau = (x-z)/deno;
RealScalar w = sqrt(numext::abs2(tau) + RealScalar(1));
RealScalar t;
if(tau>RealScalar(0))

3
Eigen/src/misc/RealSvd2x2.h
View File

@ -28,7 +28,8 @@ void real_2x2_jacobi_svd(const MatrixType& matrix, Index p, Index q,
JacobiRotation<RealScalar> rot1;
RealScalar t = m.coeff(0,0) + m.coeff(1,1);
RealScalar d = m.coeff(1,0) - m.coeff(0,1);
if(d == RealScalar(0))
if(abs(d) < (std::numeric_limits<RealScalar>::min)())
{
rot1.s() = RealScalar(0);
rot1.c() = RealScalar(1);