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bugfix in blueNorm

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This commit is contained in:
Gael Guennebaud
2009-07-16 14:20:36 +02:00
parent 65fc70b750
commit 525da6a464
3 changed files with 89 additions and 84 deletions
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39
Eigen/src/Core/Dot.h
View File

@@ -304,29 +304,6 @@ MatrixBase<Derived>::stableNorm() const
return this->cwise().abs().redux(ei_scalar_hypot_op<RealScalar>());
}
/** \internal Computes ibeta^iexp by binary expansion of iexp,
* exact if ibeta is the machine base */
template<typename T> inline T bexp(int ibeta, int iexp)
{
T tbeta = T(ibeta);
T res = 1.0;
int n = iexp;
if (n<0)
{
n = - n;
tbeta = 1.0/tbeta;
}
for(;;)
{
if ((n % 2)==0)
res = res * tbeta;
n = n/2;
if (n==0) return res;
tbeta = tbeta*tbeta;
}
return res;
}
/** \returns the \em l2 norm of \c *this using the Blue's algorithm.
* A Portable Fortran Program to Find the Euclidean Norm of a Vector,
* ACM TOMS, Vol 4, Issue 1, 1978.
@@ -337,7 +314,7 @@ template<typename Derived>
inline typename NumTraits<typename ei_traits<Derived>::Scalar>::Real
MatrixBase<Derived>::blueNorm() const
{
static int nmax;
static int nmax = -1;
static Scalar b1, b2, s1m, s2m, overfl, rbig, relerr;
int n;
Scalar ax, abig, amed, asml;
@@ -355,8 +332,8 @@ MatrixBase<Derived>::blueNorm() const
// are used. For any specific computer, each of the assignment
// statements can be replaced
nbig = std::numeric_limits<int>::max(); // largest integer
ibeta = NumTraits<Scalar>::Base; // base for floating-point numbers
it = NumTraits<Scalar>::Mantissa; // number of base-beta digits in mantissa
ibeta = std::numeric_limits<Scalar>::radix; //NumTraits<Scalar>::Base; // base for floating-point numbers
it = std::numeric_limits<Scalar>::digits; //NumTraits<Scalar>::Mantissa; // number of base-beta digits in mantissa
iemin = std::numeric_limits<Scalar>::min_exponent; // minimum exponent
iemax = std::numeric_limits<Scalar>::max_exponent; // maximum exponent
rbig = std::numeric_limits<Scalar>::max(); // largest floating-point number
@@ -368,17 +345,17 @@ MatrixBase<Derived>::blueNorm() const
ei_assert(false && "the algorithm cannot be guaranteed on this computer");
}
iexp = -((1-iemin)/2);
b1 = bexp<Scalar>(ibeta, iexp); // lower boundary of midrange
b1 = std::pow(ibeta, iexp); // lower boundary of midrange
iexp = (iemax + 1 - it)/2;
b2 = bexp<Scalar>(ibeta,iexp); // upper boundary of midrange
b2 = std::pow(ibeta,iexp); // upper boundary of midrange
iexp = (2-iemin)/2;
s1m = bexp<Scalar>(ibeta,iexp); // scaling factor for lower range
s1m = std::pow(ibeta,iexp); // scaling factor for lower range
iexp = - ((iemax+it)/2);
s2m = bexp<Scalar>(ibeta,iexp); // scaling factor for upper range
s2m = std::pow(ibeta,iexp); // scaling factor for upper range
overfl = rbig*s2m; // overfow boundary for abig
eps = bexp<Scalar>(ibeta, 1-it);
eps = std::pow(ibeta, 1-it);
relerr = ei_sqrt(eps); // tolerance for neglecting asml
abig = 1.0/eps - 1.0;
if (Scalar(nbig)>abig) nmax = abig; // largest safe n

8
Eigen/src/Core/NumTraits.h
View File

@@ -70,9 +70,7 @@ template<> struct NumTraits<float>
HasFloatingPoint = 1,
ReadCost = 1,
AddCost = 1,
MulCost = 1,
Base = 2,
Mantissa = 23
MulCost = 1
};
};
@@ -85,9 +83,7 @@ template<> struct NumTraits<double>
HasFloatingPoint = 1,
ReadCost = 1,
AddCost = 1,
MulCost = 1,
Base = 2,
Mantissa = 52
MulCost = 1
};
};