about summary refs log tree commit diff
path: root/sysdeps/ieee754/ldbl-128/s_cbrtl.c
diff options
context:
space:
mode:
authorUlrich Drepper <drepper@redhat.com>2001-10-14 22:33:08 +0000
committerUlrich Drepper <drepper@redhat.com>2001-10-14 22:33:08 +0000
commit1f5649f86b7de5aec990e03f2700df36a01c2752 (patch)
treec6126aff7f80434c64f21dd6033215864afd57cd /sysdeps/ieee754/ldbl-128/s_cbrtl.c
parent459a31635e9fe474c05e995312fde318d7c4a5b0 (diff)
downloadglibc-1f5649f86b7de5aec990e03f2700df36a01c2752.tar.gz
glibc-1f5649f86b7de5aec990e03f2700df36a01c2752.tar.xz
glibc-1f5649f86b7de5aec990e03f2700df36a01c2752.zip
Update.
2001-10-14  Ulrich Drepper  <drepper@redhat.com>

	* locale/programs/ld-collate.c (handle_ellipsis): Use %lX not %lx
	to generate hexadecimal identifier.
	Patch by Jungshik Shin <jungshik.shin@yale.edu>.

2001-10-09  Stephen L Moshier  <moshier@mediaone.net>

	* sysdeps/ieee754/ldbl-96/s_cbrtl.c (__cbrtl): Fix algorithm.

2001-10-14  Ulrich Drepper  <drepper@redhat.com>

	* sysdeps/ieee754/ldbl-128/e_powl.c: New file.
	* sysdeps/ieee754/ldbl-128/s_cbrtl.c: New file.
	Contributed by Stephen L Moshier <moshier@mediaone.net>.

	* sysdeps/ieee754/ldbl-128/e_j0l.c: Constify float variables.
	* sysdeps/ieee754/ldbl-128/e_j1l.c: Likewise.
	* sysdeps/ieee754/ldbl-128/e_lgammal_r.c: Likewise
	* sysdeps/ieee754/ldbl-128/s_erfl.c: Likewise
	* sysdeps/ieee754/ldbl-128/s_expm1l.c: Likewise
	* sysdeps/ieee754/ldbl-128/s_log1pl.c: Likewise

	* timezone/africa: Update from tzdata2001d.
	* timezone/asia: Likewise.
	* timezone/australasia: Likewise.
	* timezone/backward: Likewise.
	* timezone/europe: Likewise.
	* timezone/leapseconds: Likewise.
	* timezone/northamerica: Likewise.
	* timezone/southamerica: Likewise.
	* timezone/zone.tab: Likewise.

2001-10-09  Martin Schwidefsky  <schwidefsky@de.ibm.com>

	* sysdeps/s390/s390-32/sys/ucontext.h: Correct __psw_t typedef.
	* sysdeps/s390/s390-64/sys/ucontext.h: Likewise.
Diffstat (limited to 'sysdeps/ieee754/ldbl-128/s_cbrtl.c')
-rw-r--r--sysdeps/ieee754/ldbl-128/s_cbrtl.c121
1 files changed, 121 insertions, 0 deletions
diff --git a/sysdeps/ieee754/ldbl-128/s_cbrtl.c b/sysdeps/ieee754/ldbl-128/s_cbrtl.c
new file mode 100644
index 0000000000..298754ea74
--- /dev/null
+++ b/sysdeps/ieee754/ldbl-128/s_cbrtl.c
@@ -0,0 +1,121 @@
+/*							cbrtl.c
+ *
+ *	Cube root, long double precision
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * long double x, y, cbrtl();
+ *
+ * y = cbrtl( x );
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Returns the cube root of the argument, which may be negative.
+ *
+ * Range reduction involves determining the power of 2 of
+ * the argument.  A polynomial of degree 2 applied to the
+ * mantissa, and multiplication by the cube root of 1, 2, or 4
+ * approximates the root to within about 0.1%.  Then Newton's
+ * iteration is used three times to converge to an accurate
+ * result.
+ *
+ *
+ *
+ * ACCURACY:
+ *
+ *                      Relative error:
+ * arithmetic   domain     # trials      peak         rms
+ *    IEEE       -8,8       100000      1.3e-34     3.9e-35
+ *    IEEE    exp(+-707)    100000      1.3e-34     4.3e-35
+ *
+ */
+
+/*
+Cephes Math Library Release 2.2: January, 1991
+Copyright 1984, 1991 by Stephen L. Moshier
+Adapted for glibc October, 2001.
+*/
+
+#include "math.h"
+#include "math_private.h"
+
+static const long double CBRT2 = 1.259921049894873164767210607278228350570251L;
+static const long double CBRT4 = 1.587401051968199474751705639272308260391493L;
+static const long double CBRT2I = 0.7937005259840997373758528196361541301957467L;
+static const long double CBRT4I = 0.6299605249474365823836053036391141752851257L;
+
+
+long double
+__cbrtl (long double x)
+{
+  int e, rem, sign;
+  long double z;
+
+  if (!__finitel (x))
+    return x + x;
+
+  if (x == 0)
+    return (x);
+
+  if (x > 0)
+    sign = 1;
+  else
+    {
+      sign = -1;
+      x = -x;
+    }
+
+  z = x;
+ /* extract power of 2, leaving mantissa between 0.5 and 1  */
+  x = __frexpl (x, &e);
+
+  /* Approximate cube root of number between .5 and 1,
+     peak relative error = 1.2e-6  */
+  x = ((((1.3584464340920900529734e-1L * x
+	  - 6.3986917220457538402318e-1L) * x
+	 + 1.2875551670318751538055e0L) * x
+	- 1.4897083391357284957891e0L) * x
+       + 1.3304961236013647092521e0L) * x + 3.7568280825958912391243e-1L;
+
+  /* exponent divided by 3 */
+  if (e >= 0)
+    {
+      rem = e;
+      e /= 3;
+      rem -= 3 * e;
+      if (rem == 1)
+	x *= CBRT2;
+      else if (rem == 2)
+	x *= CBRT4;
+    }
+  else
+    {				/* argument less than 1 */
+      e = -e;
+      rem = e;
+      e /= 3;
+      rem -= 3 * e;
+      if (rem == 1)
+	x *= CBRT2I;
+      else if (rem == 2)
+	x *= CBRT4I;
+      e = -e;
+    }
+
+  /* multiply by power of 2 */
+  x = __ldexpl (x, e);
+
+  /* Newton iteration */
+  x -= (x - (z / (x * x))) * 0.3333333333333333333333333333333333333333L;
+  x -= (x - (z / (x * x))) * 0.3333333333333333333333333333333333333333L;
+  x -= (x - (z / (x * x))) * 0.3333333333333333333333333333333333333333L;
+
+  if (sign < 0)
+    x = -x;
+  return (x);
+}
+
+weak_alias (__cbrtl, cbrtl)