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std_complex.h (_Norm_helper): New class template. 

* include/bits/std_complex.h (_Norm_helper): New class template.
       (norm): Tweak.

From-SVN: r46690
This commit is contained in:
Gabriel Dos Reis 2001-11-01 11:00:57 +00:00 committed by Gabriel Dos Reis
parent 9199347f9a
commit 3c4e7c5081
2 changed files with 35 additions and 2 deletions
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5
libstdc++-v3/ChangeLog
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@ -1,3 +1,8 @@
2001-11-01 Gabriel Dos Reis <gdr@merlin.codesourcery.com>
* include/bits/std_complex.h (_Norm_helper): New class template.
(norm): Tweak.
2001-10-31 Benjamin Kosnik <bkoz@redhat.com>
libstdc++/4749

32
libstdc++-v3/include/bits/std_complex.h
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@ -40,6 +40,7 @@
#pragma GCC system_header
#include <bits/c++config.h>
#include <bits/cpp_type_traits.h>
#include <bits/std_cmath.h>
#include <bits/std_sstream.h>
@ -417,12 +418,39 @@ namespace std
arg(const complex<_Tp>& __z)
{ return atan2(__z.imag(), __z.real()); }
// 26.2.7/5: norm(__z) returns the squared magintude of __z.
// As defined, norm() is -not- a norm is the common mathematical
// sens used in numerics. The helper class _Norm_helper<> tries to
// distinguish between builtin floating point and the rest, so as
// to deliver an answer as close as possible to the real value.
template<bool>
struct _Norm_helper
{
template<typename _Tp>
static inline _Tp _S_do_it(const complex<_Tp>& __z)
{
const _Tp __x = __z.real();
const _Tp __y = __z.imag();
return __x * __x + __y * __y;
}
};
template<>
struct _Norm_helper<true>
{
template<typename _Tp>
static inline _Tp _S_do_it(const complex<_Tp>& __z)
{
_Tp __res = abs(__z);
return __res * __res;
}
};
template<typename _Tp>
inline _Tp
norm(const complex<_Tp>& __z)
{
_Tp __res = abs(__z);
return __res * __res;
return _Norm_helper<__is_floating<_Tp>::_M_type>::_S_do_it(__z);
}
template<typename _Tp>