--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2011-10-06  Bruno Haible  <bruno@clisp.org>
+
+	New module 'frexpf'.
+	* lib/math.in.h (frexpf): New declaration.
+	* lib/frexpf.c: New file.
+	* m4/frexpf.m4: New file.
+	* m4/math_h.m4 (gl_MATH_H): Test whether frexpf is declared.
+	(gl_MATH_H_DEFAULTS): Initialize GNULIB_FREXPF, HAVE_FREXPF.
+	* modules/math (Makefile.am): Substitute GNULIB_FREXPF, HAVE_FREXPF.
+	* modules/frexpf: New file.
+	* tests/test-math-c++.cc: Check the declaration of frexpf.
+	* doc/posix-functions/frexpf.texi: Mention the new module.
+
 2011-10-06  Bruno Haible  <bruno@clisp.org>
 
 	math: Sort function declarations of math.in.h.

--- a/doc/posix-functions/frexpf.texi
+++ b/doc/posix-functions/frexpf.texi
@@ -4,14 +4,10 @@
 
 POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/frexpf.html}
 
-Gnulib module: ---
+Gnulib module: frexpf
 
 Portability problems fixed by Gnulib:
 @itemize
-@end itemize
-
-Portability problems not fixed by Gnulib:
-@itemize
 @item
 This function is missing on some platforms:
 Minix 3.1.8, AIX 5.1, HP-UX 11, IRIX 6.5, Solaris 9.
@@ -19,3 +15,7 @@
 This function is only defined as a macro with arguments on some platforms:
 MSVC 9.
 @end itemize
+
+Portability problems not fixed by Gnulib:
+@itemize
+@end itemize

new file mode 100644
--- /dev/null
+++ b/lib/frexpf.c
@@ -0,0 +1,26 @@
+/* Split a float into fraction and mantissa.
+   Copyright (C) 2011 Free Software Foundation, Inc.
+
+   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>
+
+float
+frexpf (float x, int *expptr)
+{
+  return (float) frexp ((double) x, expptr);
+}

--- a/lib/math.in.h
+++ b/lib/math.in.h
@@ -342,6 +342,28 @@
      If x is zero: mantissa = x, exp = 0.
      If x is infinite or NaN: mantissa = x, exp unspecified.
    Store exp in *EXPPTR and return mantissa.  */
+#if @GNULIB_FREXPF@
+# if !@HAVE_FREXPF@
+#  undef frexpf
+_GL_FUNCDECL_SYS (frexpf, float, (float x, int *expptr) _GL_ARG_NONNULL ((2)));
+# endif
+_GL_CXXALIAS_SYS (frexpf, float, (float x, int *expptr));
+_GL_CXXALIASWARN (frexpf);
+#elif defined GNULIB_POSIXCHECK
+# undef frexpf
+# if HAVE_RAW_DECL_FREXPF
+_GL_WARN_ON_USE (frexpf, "frexpf is unportable - "
+                 "use gnulib module frexpf for portability");
+# endif
+#endif
+
+/* Write x as
+     x = mantissa * 2^exp
+   where
+     If x finite and nonzero: 0.5 <= |mantissa| < 1.0.
+     If x is zero: mantissa = x, exp = 0.
+     If x is infinite or NaN: mantissa = x, exp unspecified.
+   Store exp in *EXPPTR and return mantissa.  */
 #if @GNULIB_FREXP@
 # if @REPLACE_FREXP@
 #  if !(defined __cplusplus && defined GNULIB_NAMESPACE)

new file mode 100644
--- /dev/null
+++ b/m4/frexpf.m4
@@ -0,0 +1,25 @@
+# frexpf.m4 serial 1
+dnl Copyright (C) 2011 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_FREXPF],
+[
+  AC_REQUIRE([gl_MATH_H_DEFAULTS])
+  AC_REQUIRE([gl_FUNC_FREXP])
+
+  dnl Test whether frexpf() exists. Assume that frexpf(), if it exists, is
+  dnl defined in the same library as frexp().
+  save_LIBS="$LIBS"
+  LIBS="$LIBS $FREXP_LIBM"
+  AC_CHECK_FUNCS([frexpf])
+  LIBS="$save_LIBS"
+  if test $ac_cv_func_frexpf = yes; then
+    FREXPF_LIBM="$FREXP_LIBM"
+  else
+    HAVE_FREXPF=0
+    FREXPF_LIBM="$FREXP_LIBM"
+  fi
+  AC_SUBST([FREXPF_LIBM])
+])

--- a/m4/math_h.m4
+++ b/m4/math_h.m4
@@ -1,4 +1,4 @@
-# math_h.m4 serial 28
+# math_h.m4 serial 29
 dnl Copyright (C) 2007-2011 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -39,7 +39,8 @@
   dnl Check for declarations of anything we want to poison if the
   dnl corresponding gnulib module is not in use.
   gl_WARN_ON_USE_PREPARE([[#include <math.h>]],
-    [acosl asinl atanl ceilf ceill cosl expl fabsf floorf floorl fmodf frexpl
+    [acosl asinl atanl ceilf ceill cosl expl fabsf floorf floorl fmodf
+     frexpf frexpl
      ldexpl logb logl modff round roundf roundl sinl sqrtl
      tanl trunc truncf truncl])
 ])
@@ -68,6 +69,7 @@
   GNULIB_FLOORF=0;   AC_SUBST([GNULIB_FLOORF])
   GNULIB_FLOORL=0;   AC_SUBST([GNULIB_FLOORL])
   GNULIB_FMODF=0;    AC_SUBST([GNULIB_FMODF])
+  GNULIB_FREXPF=0;   AC_SUBST([GNULIB_FREXPF])
   GNULIB_FREXP=0;    AC_SUBST([GNULIB_FREXP])
   GNULIB_FREXPL=0;   AC_SUBST([GNULIB_FREXPL])
   GNULIB_ISFINITE=0; AC_SUBST([GNULIB_ISFINITE])
@@ -98,6 +100,7 @@
   HAVE_EXPL=1;                 AC_SUBST([HAVE_EXPL])
   HAVE_FABSF=1;                AC_SUBST([HAVE_FABSF])
   HAVE_FMODF=1;                AC_SUBST([HAVE_FMODF])
+  HAVE_FREXPF=1;               AC_SUBST([HAVE_FREXPF])
   HAVE_ISNANF=1;               AC_SUBST([HAVE_ISNANF])
   HAVE_ISNAND=1;               AC_SUBST([HAVE_ISNAND])
   HAVE_ISNANL=1;               AC_SUBST([HAVE_ISNANL])

new file mode 100644
--- /dev/null
+++ b/modules/frexpf
@@ -0,0 +1,31 @@
+Description:
+frexpf() function: split a float into its constituents.
+
+Files:
+lib/frexpf.c
+m4/frexpf.m4
+
+Depends-on:
+math
+frexp           [test $HAVE_FREXPF = 0]
+
+configure.ac:
+gl_FUNC_FREXPF
+if test $HAVE_FREXPF = 0; then
+  AC_LIBOBJ([frexpf])
+fi
+gl_MATH_MODULE_INDICATOR([frexpf])
+
+Makefile.am:
+
+Include:
+<math.h>
+
+Link:
+$(FREXPF_LIBM)
+
+License:
+LGPL
+
+Maintainer:
+Bruno Haible

--- a/modules/math
+++ b/modules/math
@@ -41,6 +41,7 @@
 	      -e 's/@''GNULIB_FLOORF''@/$(GNULIB_FLOORF)/g' \
 	      -e 's/@''GNULIB_FLOORL''@/$(GNULIB_FLOORL)/g' \
 	      -e 's/@''GNULIB_FMODF''@/$(GNULIB_FMODF)/g' \
+	      -e 's/@''GNULIB_FREXPF''@/$(GNULIB_FREXPF)/g' \
 	      -e 's/@''GNULIB_FREXP''@/$(GNULIB_FREXP)/g' \
 	      -e 's/@''GNULIB_FREXPL''@/$(GNULIB_FREXPL)/g' \
 	      -e 's/@''GNULIB_ISFINITE''@/$(GNULIB_ISFINITE)/g' \
@@ -71,6 +72,7 @@
 	      -e 's|@''HAVE_EXPL''@|$(HAVE_EXPL)|g' \
 	      -e 's|@''HAVE_FABSF''@|$(HAVE_FABSF)|g' \
 	      -e 's|@''HAVE_FMODF''@|$(HAVE_FMODF)|g' \
+	      -e 's|@''HAVE_FREXPF''@|$(HAVE_FREXPF)|g' \
 	      -e 's|@''HAVE_ISNANF''@|$(HAVE_ISNANF)|g' \
 	      -e 's|@''HAVE_ISNAND''@|$(HAVE_ISNAND)|g' \
 	      -e 's|@''HAVE_ISNANL''@|$(HAVE_ISNANL)|g' \

--- a/tests/test-math-c++.cc
+++ b/tests/test-math-c++.cc
@@ -43,6 +43,9 @@
 SIGNATURE_CHECK (GNULIB_NAMESPACE::fmodf, float, (float, float));
 #endif
 //SIGNATURE_CHECK (GNULIB_NAMESPACE::fmod, double, (double, double));
+#if GNULIB_TEST_FREXPF
+SIGNATURE_CHECK (GNULIB_NAMESPACE::frexpf, float, (float, int *));
+#endif
 #if GNULIB_TEST_FREXP
 SIGNATURE_CHECK (GNULIB_NAMESPACE::frexp, double, (double, int *));
 #endif