opencv/3rdparty/lapack/dlapy2.c

61 lines
1.3 KiB
C

#include "clapack.h"
doublereal dlapy2_(doublereal *x, doublereal *y)
{
/* System generated locals */
doublereal ret_val, d__1;
/* Builtin functions */
double sqrt(doublereal);
/* Local variables */
doublereal w, z__, xabs, yabs;
/* -- LAPACK auxiliary routine (version 3.1) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* DLAPY2 returns sqrt(x**2+y**2), taking care not to cause unnecessary */
/* overflow. */
/* Arguments */
/* ========= */
/* X (input) DOUBLE PRECISION */
/* Y (input) DOUBLE PRECISION */
/* X and Y specify the values x and y. */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
xabs = abs(*x);
yabs = abs(*y);
w = max(xabs,yabs);
z__ = min(xabs,yabs);
if (z__ == 0.) {
ret_val = w;
} else {
/* Computing 2nd power */
d__1 = z__ / w;
ret_val = w * sqrt(d__1 * d__1 + 1.);
}
return ret_val;
/* End of DLAPY2 */
} /* dlapy2_ */