xref: /illumos-gate/usr/src/lib/libm/common/complex/carg.c (revision ddc0e0b5)
125c28e83SPiotr Jasiukajtis /*
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2125c28e83SPiotr Jasiukajtis /*
2225c28e83SPiotr Jasiukajtis  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
2325c28e83SPiotr Jasiukajtis  */
2425c28e83SPiotr Jasiukajtis /*
2525c28e83SPiotr Jasiukajtis  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
2625c28e83SPiotr Jasiukajtis  * Use is subject to license terms.
2725c28e83SPiotr Jasiukajtis  */
2825c28e83SPiotr Jasiukajtis 
29*ddc0e0b5SRichard Lowe #pragma weak __carg = carg
3025c28e83SPiotr Jasiukajtis 
3125c28e83SPiotr Jasiukajtis #include <math.h>		/* atan2 */
3225c28e83SPiotr Jasiukajtis #include "complex_wrapper.h"
3325c28e83SPiotr Jasiukajtis 
3425c28e83SPiotr Jasiukajtis static const double
3525c28e83SPiotr Jasiukajtis 	pi	= 3.14159265358979311600e+00,
3625c28e83SPiotr Jasiukajtis 	pi_lo	= 1.22464679914735320717e-16;
3725c28e83SPiotr Jasiukajtis 
3825c28e83SPiotr Jasiukajtis double
carg(dcomplex z)3925c28e83SPiotr Jasiukajtis carg(dcomplex z) {
4025c28e83SPiotr Jasiukajtis 	int	ix, iy;
4125c28e83SPiotr Jasiukajtis 
4225c28e83SPiotr Jasiukajtis 	ix = ((int *)&(D_RE(z)))[HIWORD];
4325c28e83SPiotr Jasiukajtis 	iy = ((int *)&(D_IM(z)))[HIWORD];
4425c28e83SPiotr Jasiukajtis 	if ((((ix | iy) & ~0x80000000) | ((int *)&(D_RE(z)))[LOWORD] |
4525c28e83SPiotr Jasiukajtis 	    ((int *)&(D_IM(z)))[LOWORD]) == 0) {
4625c28e83SPiotr Jasiukajtis 		/* x and y are both zero */
4725c28e83SPiotr Jasiukajtis 		if (ix == 0)
4825c28e83SPiotr Jasiukajtis 			return (D_IM(z));
4925c28e83SPiotr Jasiukajtis 		return ((iy == 0)? pi + pi_lo : -pi - pi_lo);
5025c28e83SPiotr Jasiukajtis 	}
5125c28e83SPiotr Jasiukajtis 	return (atan2(D_IM(z), D_RE(z)));
5225c28e83SPiotr Jasiukajtis }
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