74 lines
1.6 KiB
C
74 lines
1.6 KiB
C
|
#include <math.h>
|
||
|
|
#include <float.h>
|
||
|
|
#include <errno.h>
|
||
|
|
|
||
|
|
/*
|
||
|
|
This implementation is based largely on Cephes library
|
||
|
|
function cabsl (cmplxl.c), which bears the following notice:
|
||
|
|
|
||
|
|
Cephes Math Library Release 2.1: January, 1989
|
||
|
|
Copyright 1984, 1987, 1989 by Stephen L. Moshier
|
||
|
|
Direct inquiries to 30 Frost Street, Cambridge, MA 02140
|
||
|
|
*/
|
||
|
|
|
||
|
|
/*
|
||
|
|
Modified for use in libmingwex.a
|
||
|
|
02 Sept 2002 Danny Smith <dannysmith@users.sourceforege.net>
|
||
|
|
Calls to ldexpl replaced by logbl and calls to frexpl replaced
|
||
|
|
by scalbnl to avoid duplicated range checks.
|
||
|
|
*/
|
||
|
|
|
||
|
|
extern long double __INFL;
|
||
|
|
#define PRECL 32
|
||
|
|
|
||
|
|
long double
|
||
|
|
hypotl (long double x, long double y)
|
||
|
|
{
|
||
|
|
int exx;
|
||
|
|
int eyy;
|
||
|
|
int scale;
|
||
|
|
long double xx =fabsl(x);
|
||
|
|
long double yy =fabsl(y);
|
||
|
|
if (!isfinite(xx) || !isfinite(yy))
|
||
|
|
return xx + yy; /* Return INF or NAN. */
|
||
|
|
|
||
|
|
if (xx == 0.0L)
|
||
|
|
return yy;
|
||
|
|
if (yy == 0.0L)
|
||
|
|
return xx;
|
||
|
|
|
||
|
|
/* Get exponents */
|
||
|
|
exx = logbl (xx);
|
||
|
|
eyy = logbl (yy);
|
||
|
|
|
||
|
|
/* Check if large differences in scale */
|
||
|
|
scale = exx - eyy;
|
||
|
|
if ( scale > PRECL)
|
||
|
|
return xx;
|
||
|
|
if ( scale < -PRECL)
|
||
|
|
return yy;
|
||
|
|
|
||
|
|
/* Exponent of approximate geometric mean (x 2) */
|
||
|
|
scale = (exx + eyy) >> 1;
|
||
|
|
|
||
|
|
/* Rescale: Geometric mean is now about 2 */
|
||
|
|
x = scalbnl(xx, -scale);
|
||
|
|
y = scalbnl(yy, -scale);
|
||
|
|
|
||
|
|
xx = sqrtl(x * x + y * y);
|
||
|
|
|
||
|
|
/* Check for overflow and underflow */
|
||
|
|
exx = logbl(xx);
|
||
|
|
exx += scale;
|
||
|
|
if (exx > LDBL_MAX_EXP)
|
||
|
|
{
|
||
|
|
errno = ERANGE;
|
||
|
|
return __INFL;
|
||
|
|
}
|
||
|
|
if (exx < LDBL_MIN_EXP)
|
||
|
|
return 0.0L;
|
||
|
|
|
||
|
|
/* Undo scaling */
|
||
|
|
return (scalbnl (xx, scale));
|
||
|
|
}
|