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Diffstat (limited to 'lib/mlibc/options/ansi/musl-generic-math/log2l.c')
| -rw-r--r-- | lib/mlibc/options/ansi/musl-generic-math/log2l.c | 182 |
1 files changed, 0 insertions, 182 deletions
diff --git a/lib/mlibc/options/ansi/musl-generic-math/log2l.c b/lib/mlibc/options/ansi/musl-generic-math/log2l.c deleted file mode 100644 index 722b451..0000000 --- a/lib/mlibc/options/ansi/musl-generic-math/log2l.c +++ /dev/null @@ -1,182 +0,0 @@ -/* origin: OpenBSD /usr/src/lib/libm/src/ld80/e_log2l.c */ -/* - * Copyright (c) 2008 Stephen L. Moshier <steve@moshier.net> - * - * Permission to use, copy, modify, and distribute this software for any - * purpose with or without fee is hereby granted, provided that the above - * copyright notice and this permission notice appear in all copies. - * - * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES - * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF - * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR - * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES - * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN - * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF - * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. - */ -/* - * Base 2 logarithm, long double precision - * - * - * SYNOPSIS: - * - * long double x, y, log2l(); - * - * y = log2l( x ); - * - * - * DESCRIPTION: - * - * Returns the base 2 logarithm of x. - * - * The argument is separated into its exponent and fractional - * parts. If the exponent is between -1 and +1, the (natural) - * logarithm of the fraction is approximated by - * - * log(1+x) = x - 0.5 x**2 + x**3 P(x)/Q(x). - * - * Otherwise, setting z = 2(x-1)/x+1), - * - * log(x) = z + z**3 P(z)/Q(z). - * - * - * ACCURACY: - * - * Relative error: - * arithmetic domain # trials peak rms - * IEEE 0.5, 2.0 30000 9.8e-20 2.7e-20 - * IEEE exp(+-10000) 70000 5.4e-20 2.3e-20 - * - * In the tests over the interval exp(+-10000), the logarithms - * of the random arguments were uniformly distributed over - * [-10000, +10000]. - */ - -#include "libm.h" - -#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024 -long double log2l(long double x) -{ - return log2(x); -} -#elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384 -/* Coefficients for ln(1+x) = x - x**2/2 + x**3 P(x)/Q(x) - * 1/sqrt(2) <= x < sqrt(2) - * Theoretical peak relative error = 6.2e-22 - */ -static const long double P[] = { - 4.9962495940332550844739E-1L, - 1.0767376367209449010438E1L, - 7.7671073698359539859595E1L, - 2.5620629828144409632571E2L, - 4.2401812743503691187826E2L, - 3.4258224542413922935104E2L, - 1.0747524399916215149070E2L, -}; -static const long double Q[] = { -/* 1.0000000000000000000000E0,*/ - 2.3479774160285863271658E1L, - 1.9444210022760132894510E2L, - 7.7952888181207260646090E2L, - 1.6911722418503949084863E3L, - 2.0307734695595183428202E3L, - 1.2695660352705325274404E3L, - 3.2242573199748645407652E2L, -}; - -/* Coefficients for log(x) = z + z^3 P(z^2)/Q(z^2), - * where z = 2(x-1)/(x+1) - * 1/sqrt(2) <= x < sqrt(2) - * Theoretical peak relative error = 6.16e-22 - */ -static const long double R[4] = { - 1.9757429581415468984296E-3L, --7.1990767473014147232598E-1L, - 1.0777257190312272158094E1L, --3.5717684488096787370998E1L, -}; -static const long double S[4] = { -/* 1.00000000000000000000E0L,*/ --2.6201045551331104417768E1L, - 1.9361891836232102174846E2L, --4.2861221385716144629696E2L, -}; -/* log2(e) - 1 */ -#define LOG2EA 4.4269504088896340735992e-1L - -#define SQRTH 0.70710678118654752440L - -long double log2l(long double x) -{ - long double y, z; - int e; - - if (isnan(x)) - return x; - if (x == INFINITY) - return x; - if (x <= 0.0) { - if (x == 0.0) - return -1/(x*x); /* -inf with divbyzero */ - return 0/0.0f; /* nan with invalid */ - } - - /* separate mantissa from exponent */ - /* Note, frexp is used so that denormal numbers - * will be handled properly. - */ - x = frexpl(x, &e); - - /* logarithm using log(x) = z + z**3 P(z)/Q(z), - * where z = 2(x-1)/x+1) - */ - if (e > 2 || e < -2) { - if (x < SQRTH) { /* 2(2x-1)/(2x+1) */ - e -= 1; - z = x - 0.5; - y = 0.5 * z + 0.5; - } else { /* 2 (x-1)/(x+1) */ - z = x - 0.5; - z -= 0.5; - y = 0.5 * x + 0.5; - } - x = z / y; - z = x*x; - y = x * (z * __polevll(z, R, 3) / __p1evll(z, S, 3)); - goto done; - } - - /* logarithm using log(1+x) = x - .5x**2 + x**3 P(x)/Q(x) */ - if (x < SQRTH) { - e -= 1; - x = 2.0*x - 1.0; - } else { - x = x - 1.0; - } - z = x*x; - y = x * (z * __polevll(x, P, 6) / __p1evll(x, Q, 7)); - y = y - 0.5*z; - -done: - /* Multiply log of fraction by log2(e) - * and base 2 exponent by 1 - * - * ***CAUTION*** - * - * This sequence of operations is critical and it may - * be horribly defeated by some compiler optimizers. - */ - z = y * LOG2EA; - z += x * LOG2EA; - z += y; - z += x; - z += e; - return z; -} -#elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384 -// TODO: broken implementation to make things compile -long double log2l(long double x) -{ - return log2(x); -} -#endif |