1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved. 24 */ 25 /* 26 * Copyright 2006 Sun Microsystems, Inc. All rights reserved. 27 * Use is subject to license terms. 28 */ 29 30 #include "libm.h" 31 #include "longdouble.h" 32 33 /* 34 * exp10l(x) 35 * n = nint(x*(log10/log2)) ; 36 * exp10(x) = 10**x = exp(x*ln(10)) = exp(n*ln2+(x*ln10-n*ln2)) 37 * = 2**n*exp(ln10*(x-n*log2/log10))) 38 * If x is an integer <= M then use repeat multiplication. For 39 * 10**M is the largest representable integer, where 40 * M = 10 single precision (24 bits) 41 * M = 22 double precision (53 bits) 42 * M = 48 quadruple precision (113 bits) 43 */ 44 45 #define TINY 1.0e-20L /* single: 1e-5, double: 1e-10, quad: 1e-20 */ 46 #define LG10OVT 4933.L /* single: 39, double: 309, quad: 4933 */ 47 #define LG10UFT -4966.L /* single: -45, double: -323, quad: -4966 */ 48 #define M 48 49 /* logt2hi : last 32 bits is zero for quad prec */ 50 #define LOGT2HI 0.30102999566398119521373889472420986034688L 51 #define LOGT2LO 2.831664213089468167896664371953e-31L 52 53 static const long double 54 zero = 0.0L, 55 tiny = TINY * TINY, 56 one = 1.0L, 57 lg10 = 3.321928094887362347870319429489390175865e+0000L, 58 ln10 = 2.302585092994045684017991454684364207601e+0000L, 59 logt2hi = LOGT2HI, 60 logt2lo = LOGT2LO, 61 lg10ovt = LG10OVT, 62 lg10uft = LG10UFT; 63 64 long double 65 exp10l(long double x) { 66 long double t, tenp; 67 int k; 68 69 if (!finitel(x)) { 70 if (isnanl(x) || x > zero) 71 return (x + x); 72 else 73 return (zero); 74 } 75 if (fabsl(x) < tiny) 76 return (one + x); 77 if (x <= lg10ovt) 78 if (x >= lg10uft) { 79 k = (int) x; 80 tenp = 10.0L; 81 /* x is a small +integer */ 82 if (0 <= k && k <= M && (long double) k == x) { 83 t = one; 84 if (k & 1) 85 t *= tenp; 86 k >>= 1; 87 while (k) { 88 tenp *= tenp; 89 if (k & 1) 90 t *= tenp; 91 k >>= 1; 92 } 93 return (t); 94 } 95 t = anintl(x * lg10); 96 return (scalbnl(expl(ln10 * ((x - t * logt2hi) - 97 t * logt2lo)), (int) t)); 98 } else 99 return (scalbnl(one, -50000)); /* underflow */ 100 else 101 return (scalbnl(one, 50000)); /* overflow */ 102 } 103