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-rw-r--r--ChangeLog6
-rw-r--r--NEWS4
-rw-r--r--sysdeps/ieee754/ldbl-128/e_log10l.c244
3 files changed, 252 insertions, 2 deletions
diff --git a/ChangeLog b/ChangeLog
index 33f337d..6f03819 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2001-11-10 Andreas Jaeger <aj@suse.de>
+
+ * sysdeps/ieee754/ldbl-128/e_log2l.c: New file.
+ * sysdeps/ieee754/ldbl-128/e_log10l.c: Likewise.
+ Contributed by Stephen L Moshier <moshier@mediaone.net>.
+
2001-11-09 Ulrich Drepper <drepper@redhat.com>
* elf/dl-minimal.c (realloc): Handle NULL for first parameter
diff --git a/NEWS b/NEWS
index 37f71b3..24df25f 100644
--- a/NEWS
+++ b/NEWS
@@ -8,8 +8,8 @@ Please send GNU C library bug reports using the `glibcbug' script to
Version 2.2.5
-* Stephen Moshier implemented powl and cbrtl for the 128-bit
- long double format.
+* Stephen Moshier implemented log2, log10, powl and cbrtl for the
+ 128-bit long double format.
* Masahide Washizawa contributed iconv modules for IBM1132, IBM1133, IBM1160,
IBM1161, and IBM1162 charsets.
diff --git a/sysdeps/ieee754/ldbl-128/e_log10l.c b/sysdeps/ieee754/ldbl-128/e_log10l.c
new file mode 100644
index 0000000..06dce3a
--- /dev/null
+++ b/sysdeps/ieee754/ldbl-128/e_log10l.c
@@ -0,0 +1,244 @@
+/* log10l.c
+ *
+ * Common logarithm, 128-bit long double precision
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * long double x, y, log10l();
+ *
+ * y = log10l( x );
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Returns the base 10 logarithm of x.
+ *
+ * The argument is separated into its exponent and fractional
+ * parts. If the exponent is between -1 and +1, the 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 2.3e-34 4.9e-35
+ * IEEE exp(+-10000) 30000 1.0e-34 4.1e-35
+ *
+ * In the tests over the interval exp(+-10000), the logarithms
+ * of the random arguments were uniformly distributed over
+ * [-10000, +10000].
+ *
+ */
+
+/*
+ Cephes Math Library Release 2.2: January, 1991
+ Copyright 1984, 1991 by Stephen L. Moshier
+ Adapted for glibc November, 2001
+ */
+
+#include "math.h"
+#include "math_private.h"
+
+/* 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 = 5.3e-37,
+ * relative peak error spread = 2.3e-14
+ */
+static const long double P[13] =
+{
+ 1.313572404063446165910279910527789794488E4L,
+ 7.771154681358524243729929227226708890930E4L,
+ 2.014652742082537582487669938141683759923E5L,
+ 3.007007295140399532324943111654767187848E5L,
+ 2.854829159639697837788887080758954924001E5L,
+ 1.797628303815655343403735250238293741397E5L,
+ 7.594356839258970405033155585486712125861E4L,
+ 2.128857716871515081352991964243375186031E4L,
+ 3.824952356185897735160588078446136783779E3L,
+ 4.114517881637811823002128927449878962058E2L,
+ 2.321125933898420063925789532045674660756E1L,
+ 4.998469661968096229986658302195402690910E-1L,
+ 1.538612243596254322971797716843006400388E-6L
+};
+static const long double Q[12] =
+{
+ 3.940717212190338497730839731583397586124E4L,
+ 2.626900195321832660448791748036714883242E5L,
+ 7.777690340007566932935753241556479363645E5L,
+ 1.347518538384329112529391120390701166528E6L,
+ 1.514882452993549494932585972882995548426E6L,
+ 1.158019977462989115839826904108208787040E6L,
+ 6.132189329546557743179177159925690841200E5L,
+ 2.248234257620569139969141618556349415120E5L,
+ 5.605842085972455027590989944010492125825E4L,
+ 9.147150349299596453976674231612674085381E3L,
+ 9.104928120962988414618126155557301584078E2L,
+ 4.839208193348159620282142911143429644326E1L
+/* 1.000000000000000000000000000000000000000E0L, */
+};
+
+/* 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 = 1.1e-35,
+ * relative peak error spread 1.1e-9
+ */
+static const long double R[6] =
+{
+ 1.418134209872192732479751274970992665513E5L,
+ -8.977257995689735303686582344659576526998E4L,
+ 2.048819892795278657810231591630928516206E4L,
+ -2.024301798136027039250415126250455056397E3L,
+ 8.057002716646055371965756206836056074715E1L,
+ -8.828896441624934385266096344596648080902E-1L
+};
+static const long double S[6] =
+{
+ 1.701761051846631278975701529965589676574E6L,
+ -1.332535117259762928288745111081235577029E6L,
+ 4.001557694070773974936904547424676279307E5L,
+ -5.748542087379434595104154610899551484314E4L,
+ 3.998526750980007367835804959888064681098E3L,
+ -1.186359407982897997337150403816839480438E2L
+/* 1.000000000000000000000000000000000000000E0L, */
+};
+
+static const long double
+/* log10(2) */
+L102A = 0.3125L,
+L102B -1.14700043360188047862611052755069732318101185E-2L,
+/* log10(e) */
+L10EA = 0.5L,
+L10EB = -6.570551809674817234887108108339491770560299E-2L,
+/* sqrt(2)/2 */
+SQRTH = 7.071067811865475244008443621048490392848359E-1L;
+
+
+
+/* Evaluate P[n] x^n + P[n-1] x^(n-1) + ... + P[0] */
+
+static long double
+neval (long double x, const long double *p, int n)
+{
+ long double y;
+
+ p += n;
+ y = *p--;
+ do
+ {
+ y = y * x + *p--;
+ }
+ while (--n > 0);
+ return y;
+}
+
+
+/* Evaluate x^n+1 + P[n] x^(n) + P[n-1] x^(n-1) + ... + P[0] */
+
+static long double
+deval (long double x, const long double *p, int n)
+{
+ long double y;
+
+ p += n;
+ y = x + *p--;
+ do
+ {
+ y = y * x + *p--;
+ }
+ while (--n > 0);
+ return y;
+}
+
+
+
+long double
+__ieee754_log10l (x)
+ long double x;
+{
+ long double z;
+ long double y;
+ int e;
+
+/* Test for domain */
+ if (x <= 0.0L)
+ {
+ if (x == 0.0L)
+ return (-1.0L / (x - x));
+ else
+ return (x - x) / (x - x);
+ }
+ if (!__finitel (x))
+ return (x + x);
+
+/* 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 - 0.5L;
+ y = 0.5L * z + 0.5L;
+ }
+ else
+ { /* 2 (x-1)/(x+1) */
+ z = x - 0.5L;
+ z -= 0.5L;
+ y = 0.5L * x + 0.5L;
+ }
+ x = z / y;
+ z = x * x;
+ y = x * (z * neval (z, R, 5) / deval (z, S, 5));
+ 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 - 1.0L; /* 2x - 1 */
+ }
+ else
+ {
+ x = x - 1.0L;
+ }
+ z = x * x;
+ y = x * (z * neval (x, P, 12) / deval (x, Q, 11));
+ y = y - 0.5 * z;
+
+done:
+
+ /* Multiply log of fraction by log10(e)
+ * and base 2 exponent by log10(2).
+ */
+ z = y * L10EB;
+ z += x * L10EB;
+ z += e * L102B;
+ z += y * L10EA;
+ z += x * L10EA;
+ z += e * L102A;
+ return (z);
+}
generated by cgit v1.1 at 2024-11-09 19:27:48 +0000