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/* lapack/double/dlapy2.f -- translated by f2c (version 20050501).
You must link the resulting object file with libf2c:
on Microsoft Windows system, link with libf2c.lib;
on Linux or Unix systems, link with .../path/to/libf2c.a -lm
or, if you install libf2c.a in a standard place, with -lf2c -lm
-- in that order, at the end of the command line, as in
cc *.o -lf2c -lm
Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
http://www.netlib.org/f2c/libf2c.zip
*/
#ifdef __cplusplus
extern "C" {
#endif
#include "v3p_netlib.h"
/*< DOUBLE PRECISION FUNCTION DLAPY2( X, Y ) >*/
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 3.0) -- */
/* Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., */
/* Courant Institute, Argonne National Lab, and Rice University */
/* October 31, 1992 */
/* .. Scalar Arguments .. */
/*< DOUBLE PRECISION X, Y >*/
/* .. */
/* 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 .. */
/*< DOUBLE PRECISION ZERO >*/
/*< PARAMETER ( ZERO = 0.0D0 ) >*/
/*< DOUBLE PRECISION ONE >*/
/*< PARAMETER ( ONE = 1.0D0 ) >*/
/* .. */
/* .. Local Scalars .. */
/*< DOUBLE PRECISION W, XABS, YABS, Z >*/
/* .. */
/* .. Intrinsic Functions .. */
/*< INTRINSIC ABS, MAX, MIN, SQRT >*/
/* .. */
/* .. Executable Statements .. */
/*< XABS = ABS( X ) >*/
xabs = abs(*x);
/*< YABS = ABS( Y ) >*/
yabs = abs(*y);
/*< W = MAX( XABS, YABS ) >*/
w = max(xabs,yabs);
/*< Z = MIN( XABS, YABS ) >*/
z__ = min(xabs,yabs);
/*< IF( Z.EQ.ZERO ) THEN >*/
if (z__ == 0.) {
/*< DLAPY2 = W >*/
ret_val = w;
/*< ELSE >*/
} else {
/*< DLAPY2 = W*SQRT( ONE+( Z / W )**2 ) >*/
/* Computing 2nd power */
d__1 = z__ / w;
ret_val = w * sqrt(d__1 * d__1 + 1.);
/*< END IF >*/
}
/*< RETURN >*/
return ret_val;
/* End of DLAPY2 */
/*< END >*/
} /* dlapy2_ */
#ifdef __cplusplus
}
#endif
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