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Optimize getting exponent from IEEE floating points.

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jdh8
2012-08-08 01:27:11 +08:00
parent 93967b0dd6 a1b405c92e
commit 8cddcaf839
3 changed files with 24 additions and 15 deletions
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22
unsupported/Eigen/src/MatrixFunctions/MatrixExponential.h
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@@ -13,12 +13,7 @@
#include "StemFunction.h"
namespace Eigen {
#if defined(_MSC_VER) || defined(__FreeBSD__)
template <typename Scalar> Scalar log2(Scalar v) { using std::log; return log(v)/log(Scalar(2)); }
#endif
namespace Eigen {
/** \ingroup MatrixFunctions_Module
* \brief Class for computing the matrix exponential.
@@ -297,7 +292,8 @@ void MatrixExponential<MatrixType>::computeUV(float)
pade5(m_M);
} else {
const float maxnorm = 3.925724783138660f;
m_squarings = (max)(0, (int)ceil(log2(m_l1norm / maxnorm)));
frexp(m_l1norm / maxnorm, &m_squarings);
if (m_squarings < 0) m_squarings = 0;
MatrixType A = m_M / pow(Scalar(2), m_squarings);
pade7(A);
}
@@ -319,7 +315,8 @@ void MatrixExponential<MatrixType>::computeUV(double)
pade9(m_M);
} else {
const double maxnorm = 5.371920351148152;
m_squarings = (max)(0, (int)ceil(log2(m_l1norm / maxnorm)));
frexp(m_l1norm / maxnorm, &m_squarings);
if (m_squarings < 0) m_squarings = 0;
MatrixType A = m_M / pow(Scalar(2), m_squarings);
pade13(A);
}
@@ -344,7 +341,8 @@ void MatrixExponential<MatrixType>::computeUV(long double)
pade9(m_M);
} else {
const long double maxnorm = 4.0246098906697353063L;
m_squarings = (max)(0, (int)ceil(log2(m_l1norm / maxnorm)));
frexp(m_l1norm / maxnorm, &m_squarings);
if (m_squarings < 0) m_squarings = 0;
MatrixType A = m_M / pow(Scalar(2), m_squarings);
pade13(A);
}
@@ -361,7 +359,8 @@ void MatrixExponential<MatrixType>::computeUV(long double)
pade13(m_M);
} else {
const long double maxnorm = 3.2579440895405400856599663723517L;
m_squarings = (max)(0, (int)ceil(log2(m_l1norm / maxnorm)));
frexp(m_l1norm / maxnorm, &m_squarings);
if (m_squarings < 0) m_squarings = 0;
MatrixType A = m_M / pow(Scalar(2), m_squarings);
pade17(A);
}
@@ -378,7 +377,8 @@ void MatrixExponential<MatrixType>::computeUV(long double)
pade13(m_M);
} else {
const long double maxnorm = 2.884233277829519311757165057717815L;
m_squarings = (max)(0, (int)ceil(log2(m_l1norm / maxnorm)));
frexp(m_l1norm / maxnorm, &m_squarings);
if (m_squarings < 0) m_squarings = 0;
MatrixType A = m_M / pow(Scalar(2), m_squarings);
pade17(A);
}