1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2007 David Schultz <das (at) FreeBSD.ORG> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD: head/lib/msun/src/s_csqrtf.c 336412 2018-07-17 12:01:59Z bde $"); 31 32 #include <complex.h> 33 #include <math.h> 34 35 #include "math_private.h" 36 37 float complex 38 csqrtf(float complex z) 39 { 40 double t; 41 float a, b; 42 43 a = creal(z); 44 b = cimag(z); 45 46 /* Handle special cases. */ 47 if (z == 0) 48 return (CMPLXF(0, b)); 49 if (isinf(b)) 50 return (CMPLXF(INFINITY, b)); 51 if (isnan(a)) { 52 t = (b - b) / (b - b); /* raise invalid if b is not a NaN */ 53 return (CMPLXF(a + 0.0L + t, a + 0.0L + t)); /* NaN + NaN i */ 54 } 55 if (isinf(a)) { 56 /* 57 * csqrtf(inf + NaN i) = inf + NaN i 58 * csqrtf(inf + y i) = inf + 0 i 59 * csqrtf(-inf + NaN i) = NaN +- inf i 60 * csqrtf(-inf + y i) = 0 + inf i 61 */ 62 if (signbit(a)) 63 return (CMPLXF(fabsf(b - b), copysignf(a, b))); 64 else 65 return (CMPLXF(a, copysignf(b - b, b))); 66 } 67 if (isnan(b)) { 68 t = (a - a) / (a - a); /* raise invalid */ 69 return (CMPLXF(b + 0.0L + t, b + 0.0L + t)); /* NaN + NaN i */ 70 } 71 72 /* 73 * We compute t in double precision to avoid overflow and to 74 * provide correct rounding in nearly all cases. 75 * This is Algorithm 312, CACM vol 10, Oct 1967. 76 */ 77 if (a >= 0) { 78 t = sqrt((a + hypot(a, b)) * 0.5); 79 return (CMPLXF(t, b / (2 * t))); 80 } else { 81 t = sqrt((-a + hypot(a, b)) * 0.5); 82 return (CMPLXF(fabsf(b) / (2 * t), copysignf(t, b))); 83 } 84 } 85
