| Rich Felker | f681975 | 2012-04-30 03:26:53 -0400 | [diff] [blame] | 1 | #define _GNU_SOURCE |
| 2 | #include <math.h> |
| Szabolcs Nagy | 18daae3 | 2014-09-18 17:02:24 +0200 | [diff] [blame] | 3 | #include <stdint.h> |
| Rich Felker | a917c03 | 2012-05-01 00:07:37 -0400 | [diff] [blame] | 4 | #include "libc.h" |
| Rich Felker | f681975 | 2012-04-30 03:26:53 -0400 | [diff] [blame] | 5 | |
| 6 | double exp10(double x) |
| 7 | { |
| 8 | static const double p10[] = { |
| 9 | 1e-15, 1e-14, 1e-13, 1e-12, 1e-11, 1e-10, |
| 10 | 1e-9, 1e-8, 1e-7, 1e-6, 1e-5, 1e-4, 1e-3, 1e-2, 1e-1, |
| 11 | 1, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9, |
| 12 | 1e10, 1e11, 1e12, 1e13, 1e14, 1e15 |
| 13 | }; |
| 14 | double n, y = modf(x, &n); |
| Szabolcs Nagy | 18daae3 | 2014-09-18 17:02:24 +0200 | [diff] [blame] | 15 | union {double f; uint64_t i;} u = {n}; |
| 16 | /* fabs(n) < 16 without raising invalid on nan */ |
| 17 | if ((u.i>>52 & 0x7ff) < 0x3ff+4) { |
| Rich Felker | f681975 | 2012-04-30 03:26:53 -0400 | [diff] [blame] | 18 | if (!y) return p10[(int)n+15]; |
| 19 | y = exp2(3.32192809488736234787031942948939 * y); |
| 20 | return y * p10[(int)n+15]; |
| 21 | } |
| 22 | return pow(10.0, x); |
| 23 | } |
| Rich Felker | a917c03 | 2012-05-01 00:07:37 -0400 | [diff] [blame] | 24 | |
| 25 | weak_alias(exp10, pow10); |