devtools/eigen
1
0
Fork 0
mirror of https://gitlab.com/libeigen/eigen.git synced 2026-04-10 11:34:33 +08:00
Code Issues Packages Projects Releases Wiki Activity

Improve random number generation for integer and add unit test

Browse Source
This commit is contained in:
Gael Guennebaud
2015-03-19 15:10:36 +01:00
parent cc0f89eb3b
commit f329d0908a
3 changed files with 103 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
Eigen/src/Core/MathFunctions.h
View File

@@ -522,28 +522,24 @@ struct meta_floor_log2<n, lower, upper, meta_floor_log2_bogus>
template<typename Scalar>
struct random_default_impl<Scalar, false, true>
{
typedef typename NumTraits<Scalar>::NonInteger NonInteger;
static inline Scalar run(const Scalar& x, const Scalar& y)
{
using std::max;
Scalar range = (max)(Scalar(0),Scalar(y-x));
Scalar offset = 0;
if(range<=RAND_MAX)
{
// rejection sampling
int divisor = RAND_MAX/(range+1);
using std::min;
typedef typename conditional<NumTraits<Scalar>::IsSigned,std::ptrdiff_t,std::size_t>::type ScalarX;
if(y<x)
return x;
std::size_t range = ScalarX(y)-ScalarX(x);
std::size_t offset = 0;
// rejection sampling
std::size_t divisor = (range+RAND_MAX-1)/(range+1);
std::size_t multiplier = (range+RAND_MAX-1)/std::size_t(RAND_MAX);
do {
offset = Scalar(std::rand() / divisor);
} while (offset > range);
}
else
{
offset = std::rand() * range;
}
return x + offset;
do {
offset = ( (std::size_t(std::rand()) * multiplier) / divisor );
} while (offset > range);
return Scalar(ScalarX(x) + offset);
}
static inline Scalar run()