New module 'cbrtl'.

* lib/math.in.h (cbrtl): New declaration.
* lib/cbrtl.c: New file.
* m4/cbrtl.m4: New file.
* m4/math_h.m4 (gl_MATH_H): Test whether cbrtl is declared.
(gl_MATH_H_DEFAULTS): Initialize GNULIB_CBRTL, HAVE_CBRTL,
HAVE_DECL_CBRTL.
* modules/math (Makefile.am): Substitute GNULIB_CBRTL, HAVE_CBRTL,
HAVE_DECL_CBRTL.
* modules/cbrtl: New file.
* tests/test-math-c++.cc: Check the declaration of cbrtl.
* doc/posix-functions/cbrtl.texi: Mention the new module.

9 files changed, 275 insertions, 5 deletions

diff --git a/ChangeLog b/ChangeLog
index b989460474..b4451391e2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,20 @@
 2012-02-29  Bruno Haible  <bruno@clisp.org>
 
+	New module 'cbrtl'.
+	* lib/math.in.h (cbrtl): New declaration.
+	* lib/cbrtl.c: New file.
+	* m4/cbrtl.m4: New file.
+	* m4/math_h.m4 (gl_MATH_H): Test whether cbrtl is declared.
+	(gl_MATH_H_DEFAULTS): Initialize GNULIB_CBRTL, HAVE_CBRTL,
+	HAVE_DECL_CBRTL.
+	* modules/math (Makefile.am): Substitute GNULIB_CBRTL, HAVE_CBRTL,
+	HAVE_DECL_CBRTL.
+	* modules/cbrtl: New file.
+	* tests/test-math-c++.cc: Check the declaration of cbrtl.
+	* doc/posix-functions/cbrtl.texi: Mention the new module.
+
+2012-02-29  Bruno Haible  <bruno@clisp.org>
+
 	Tests for module 'cbrtf'.
 	* modules/cbrtf-tests: New file.
 	* tests/test-cbrtf.c: New file.
diff --git a/doc/posix-functions/cbrtl.texi b/doc/posix-functions/cbrtl.texi
index 9faaa28dc0..35ab013e67 100644
--- a/doc/posix-functions/cbrtl.texi
+++ b/doc/posix-functions/cbrtl.texi
@@ -4,15 +4,18 @@
 
 POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/cbrtl.html}
 
-Gnulib module: ---
+Gnulib module: cbrtl
 
 Portability problems fixed by Gnulib:
 @itemize
+@item
+This function is missing on some platforms:
+FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, HP-UX 11, Solaris 9, Cygwin, MSVC 9, Interix 3.5, BeOS.
+@item
+This function is not declared on some platforms:
+IRIX 6.5.
 @end itemize
 
 Portability problems not fixed by Gnulib:
 @itemize
-@item
-This function is missing on some platforms:
-FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, HP-UX 11, IRIX 6.5, Solaris 9, Cygwin, MSVC 9, Interix 3.5, BeOS.
 @end itemize
diff --git a/lib/cbrtl.c b/lib/cbrtl.c
new file mode 100644
index 0000000000..fe635f8824
--- /dev/null
+++ b/lib/cbrtl.c
@@ -0,0 +1,146 @@
+/* Compute cubic root of long double value.
+   Copyright (C) 2012 Free Software Foundation, Inc.
+   Cephes Math Library Release 2.2: January, 1991
+   Copyright 1984, 1991 by Stephen L. Moshier
+   Adapted for glibc October, 2001.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <math.h>
+
+#if HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
+
+long double
+cbrtl (long double x)
+{
+  return cbrt (x);
+}
+
+#else
+
+/* Code based on glibc/sysdeps/ieee754/ldbl-128/s_cbrtl.c.  */
+
+/*                                                      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
+ *
+ */
+
+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)
+{
+  if (isfinite (x) && x != 0.0L)
+    {
+      int e, rem, sign;
+      long double z;
+
+      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;
+    }
+  else
+    return x + x;
+}
+
+#endif
diff --git a/lib/math.in.h b/lib/math.in.h
index 9515424e4f..e435c7f32e 100644
--- a/lib/math.in.h
+++ b/lib/math.in.h
@@ -316,6 +316,20 @@ _GL_WARN_ON_USE (cbrt, "cbrt is unportable - "
 # endif
 #endif
 
+#if @GNULIB_CBRTL@
+# if !@HAVE_DECL_CBRTL@
+_GL_FUNCDECL_SYS (cbrtl, long double, (long double x));
+# endif
+_GL_CXXALIAS_SYS (cbrtl, long double, (long double x));
+_GL_CXXALIASWARN (cbrtl);
+#elif defined GNULIB_POSIXCHECK
+# undef cbrtl
+# if HAVE_RAW_DECL_CBRTL
+_GL_WARN_ON_USE (cbrtl, "cbrtl is unportable - "
+                 "use gnulib module cbrtl for portability");
+# endif
+#endif
+
 
 #if @GNULIB_CEILF@
 # if @REPLACE_CEILF@
diff --git a/m4/cbrtl.m4 b/m4/cbrtl.m4
new file mode 100644
index 0000000000..3f02abcc30
--- /dev/null
+++ b/m4/cbrtl.m4
@@ -0,0 +1,47 @@
+# cbrtl.m4 serial 1
+dnl Copyright (C) 2012 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_CBRTL],
+[
+  AC_REQUIRE([gl_MATH_H_DEFAULTS])
+  AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
+  AC_REQUIRE([gl_FUNC_CBRT])
+
+  dnl Test whether cbrtl() exists. Assume that cbrtl(), if it exists, is
+  dnl defined in the same library as cbrt().
+  save_LIBS="$LIBS"
+  LIBS="$LIBS $CBRT_LIBM"
+  AC_CHECK_FUNCS([cbrtl])
+  LIBS="$save_LIBS"
+  if test $ac_cv_func_cbrtl = yes; then
+    CBRTL_LIBM="$CBRT_LIBM"
+    dnl Also check whether it's declared.
+    dnl IRIX 6.5 has cbrtl() in libm but doesn't declare it in <math.h>.
+    AC_CHECK_DECL([cbrtl], , [HAVE_DECL_CBRTL=0], [[#include <math.h>]])
+  else
+    HAVE_CBRTL=0
+    HAVE_DECL_CBRTL=0
+    dnl Find libraries needed to link lib/cbrtl.c.
+    if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then
+      CBRTL_LIBM="$CBRT_LIBM"
+    else
+      AC_REQUIRE([gl_FUNC_FREXPL])
+      AC_REQUIRE([gl_FUNC_LDEXPL])
+      CBRTL_LIBM=
+      dnl Append $FREXPL_LIBM to CBRTL_LIBM, avoiding gratuitous duplicates.
+      case " $CBRTL_LIBM " in
+        *" $FREXPL_LIBM "*) ;;
+        *) CBRTL_LIBM="$CBRTL_LIBM $FREXPL_LIBM" ;;
+      esac
+      dnl Append $LDEXPL_LIBM to CBRTL_LIBM, avoiding gratuitous duplicates.
+      case " $CBRTL_LIBM " in
+        *" $LDEXPL_LIBM "*) ;;
+        *) CBRTL_LIBM="$CBRTL_LIBM $LDEXPL_LIBM" ;;
+      esac
+    fi
+  fi
+  AC_SUBST([CBRTL_LIBM])
+])
diff --git a/m4/math_h.m4 b/m4/math_h.m4
index 512589867e..d427c1a90b 100644
--- a/m4/math_h.m4
+++ b/m4/math_h.m4
@@ -40,7 +40,7 @@ AC_DEFUN([gl_MATH_H],
   dnl corresponding gnulib module is not in use.
   gl_WARN_ON_USE_PREPARE([[#include <math.h>]],
     [acosf acosl asinf asinl atanf atanl
-     cbrt cbrtf ceilf ceill copysign copysignf copysignl cosf cosl coshf
+     cbrt cbrtf cbrtl ceilf ceill copysign copysignf copysignl cosf cosl coshf
      expf expl fabsf fabsl floorf floorl fma fmaf fmal
      fmod fmodf fmodl frexpf frexpl hypotf hypotl
      ldexpf ldexpl logb logf logl log10f log10l modf modff modfl powf
@@ -69,6 +69,7 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
   GNULIB_ATAN2F=0;     AC_SUBST([GNULIB_ATAN2F])
   GNULIB_CBRT=0;       AC_SUBST([GNULIB_CBRT])
   GNULIB_CBRTF=0;      AC_SUBST([GNULIB_CBRTF])
+  GNULIB_CBRTL=0;      AC_SUBST([GNULIB_CBRTL])
   GNULIB_CEIL=0;       AC_SUBST([GNULIB_CEIL])
   GNULIB_CEILF=0;      AC_SUBST([GNULIB_CEILF])
   GNULIB_CEILL=0;      AC_SUBST([GNULIB_CEILL])
@@ -145,6 +146,7 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
   HAVE_ATAN2F=1;               AC_SUBST([HAVE_ATAN2F])
   HAVE_CBRT=1;                 AC_SUBST([HAVE_CBRT])
   HAVE_CBRTF=1;                AC_SUBST([HAVE_CBRTF])
+  HAVE_CBRTL=1;                AC_SUBST([HAVE_CBRTL])
   HAVE_COPYSIGN=1;             AC_SUBST([HAVE_COPYSIGN])
   HAVE_COPYSIGNF=1;            AC_SUBST([HAVE_COPYSIGNF])
   HAVE_COPYSIGNL=1;            AC_SUBST([HAVE_COPYSIGNL])
@@ -192,6 +194,7 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
   HAVE_DECL_ASINL=1;           AC_SUBST([HAVE_DECL_ASINL])
   HAVE_DECL_ATANL=1;           AC_SUBST([HAVE_DECL_ATANL])
   HAVE_DECL_CBRTF=1;           AC_SUBST([HAVE_DECL_CBRTF])
+  HAVE_DECL_CBRTL=1;           AC_SUBST([HAVE_DECL_CBRTL])
   HAVE_DECL_CEILF=1;           AC_SUBST([HAVE_DECL_CEILF])
   HAVE_DECL_CEILL=1;           AC_SUBST([HAVE_DECL_CEILL])
   HAVE_DECL_COSL=1;            AC_SUBST([HAVE_DECL_COSL])
diff --git a/modules/cbrtl b/modules/cbrtl
new file mode 100644
index 0000000000..ccde12fa27
--- /dev/null
+++ b/modules/cbrtl
@@ -0,0 +1,36 @@
+Description:
+cbrtl() function: cube root.
+
+Files:
+lib/cbrtl.c
+m4/cbrtl.m4
+m4/cbrt.m4
+m4/mathfunc.m4
+
+Depends-on:
+math
+cbrt            [test $HAVE_CBRTL = 0 && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1]
+isfinite        [test $HAVE_CBRTL = 0 && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 0]
+frexpl          [test $HAVE_CBRTL = 0 && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 0]
+ldexpl          [test $HAVE_CBRTL = 0 && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 0]
+
+configure.ac:
+gl_FUNC_CBRTL
+if test $HAVE_CBRTL = 0; then
+  AC_LIBOBJ([cbrtl])
+fi
+gl_MATH_MODULE_INDICATOR([cbrtl])
+
+Makefile.am:
+
+Include:
+<math.h>
+
+Link:
+$(CBRTL_LIBM)
+
+License:
+LGPL
+
+Maintainer:
+Bruno Haible
diff --git a/modules/math b/modules/math
index 26507b553d..36b05e482b 100644
--- a/modules/math
+++ b/modules/math
@@ -37,6 +37,7 @@ math.h: math.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H) $(
 	      -e 's/@''GNULIB_ATAN2F''@/$(GNULIB_ATAN2F)/g' \
 	      -e 's/@''GNULIB_CBRT''@/$(GNULIB_CBRT)/g' \
 	      -e 's/@''GNULIB_CBRTF''@/$(GNULIB_CBRTF)/g' \
+	      -e 's/@''GNULIB_CBRTL''@/$(GNULIB_CBRTL)/g' \
 	      -e 's/@''GNULIB_CEIL''@/$(GNULIB_CEIL)/g' \
 	      -e 's/@''GNULIB_CEILF''@/$(GNULIB_CEILF)/g' \
 	      -e 's/@''GNULIB_CEILL''@/$(GNULIB_CEILL)/g' \
@@ -113,6 +114,7 @@ math.h: math.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H) $(
 	      -e 's|@''HAVE_ATAN2F''@|$(HAVE_ATAN2F)|g' \
 	      -e 's|@''HAVE_CBRT''@|$(HAVE_CBRT)|g' \
 	      -e 's|@''HAVE_CBRTF''@|$(HAVE_CBRTF)|g' \
+	      -e 's|@''HAVE_CBRTL''@|$(HAVE_CBRTL)|g' \
 	      -e 's|@''HAVE_COPYSIGN''@|$(HAVE_COPYSIGN)|g' \
 	      -e 's|@''HAVE_COPYSIGNF''@|$(HAVE_COPYSIGNF)|g' \
 	      -e 's|@''HAVE_COPYSIGNL''@|$(HAVE_COPYSIGNL)|g' \
@@ -160,6 +162,7 @@ math.h: math.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H) $(
 	      -e 's|@''HAVE_DECL_ASINL''@|$(HAVE_DECL_ASINL)|g' \
 	      -e 's|@''HAVE_DECL_ATANL''@|$(HAVE_DECL_ATANL)|g' \
 	      -e 's|@''HAVE_DECL_CBRTF''@|$(HAVE_DECL_CBRTF)|g' \
+	      -e 's|@''HAVE_DECL_CBRTL''@|$(HAVE_DECL_CBRTL)|g' \
 	      -e 's|@''HAVE_DECL_CEILF''@|$(HAVE_DECL_CEILF)|g' \
 	      -e 's|@''HAVE_DECL_CEILL''@|$(HAVE_DECL_CEILL)|g' \
 	      -e 's|@''HAVE_DECL_COSL''@|$(HAVE_DECL_COSL)|g' \
diff --git a/tests/test-math-c++.cc b/tests/test-math-c++.cc
index a0a687426b..a2911be98d 100644
--- a/tests/test-math-c++.cc
+++ b/tests/test-math-c++.cc
@@ -74,6 +74,9 @@ SIGNATURE_CHECK (GNULIB_NAMESPACE::cbrtf, float, (float));
 #if GNULIB_TEST_CBRT
 SIGNATURE_CHECK (GNULIB_NAMESPACE::cbrt, double, (double));
 #endif
+#if GNULIB_TEST_CBRTL
+SIGNATURE_CHECK (GNULIB_NAMESPACE::cbrtl, long double, (long double));
+#endif
 
 #if GNULIB_TEST_CEILF
 SIGNATURE_CHECK (GNULIB_NAMESPACE::ceilf, float, (float));