--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,16 @@
 2011-10-08  Bruno Haible  <bruno@clisp.org>
 
+	New module 'expf'.
+	* lib/math.in.h (expf): New declaration.
+	* lib/expf.c: New file.
+	* m4/expf.m4: New file.
+	* m4/math_h.m4 (gl_MATH_H): Test whether expf is declared.
+	(gl_MATH_H_DEFAULTS): Initialize GNULIB_EXPF, HAVE_EXPF.
+	* modules/math (Makefile.am): Substitute GNULIB_EXPF, HAVE_EXPF.
+	* modules/expf: New file.
+	* tests/test-math-c++.cc: Check the declaration of expf.
+	* doc/posix-functions/expf.texi: Mention the new module.
+
 	exp: Use a .m4 file.
 	* m4/exp.m4: New file.
 	* modules/exp (Files): Add it.

--- a/doc/posix-functions/expf.texi
+++ b/doc/posix-functions/expf.texi
@@ -4,14 +4,10 @@
 
 POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/expf.html}
 
-Gnulib module: ---
+Gnulib module: expf
 
 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, 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/expf.c
@@ -0,0 +1,26 @@
+/* Exponential function.
+   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
+expf (float x)
+{
+  return (float) exp ((double) x);
+}

--- a/lib/math.in.h
+++ b/lib/math.in.h
@@ -228,6 +228,21 @@
 #endif
 
 
+#if @GNULIB_EXPF@
+# if !@HAVE_EXPF@
+#  undef expf
+_GL_FUNCDECL_SYS (expf, float, (float x));
+# endif
+_GL_CXXALIAS_SYS (expf, float, (float x));
+_GL_CXXALIASWARN (expf);
+#elif defined GNULIB_POSIXCHECK
+# undef expf
+# if HAVE_RAW_DECL_EXPF
+_GL_WARN_ON_USE (expf, "expf is unportable - "
+                 "use gnulib module expf for portability");
+# endif
+#endif
+
 #if @GNULIB_EXPL@
 # if !@HAVE_EXPL@ || !@HAVE_DECL_EXPL@
 _GL_FUNCDECL_SYS (expl, long double, (long double x));

new file mode 100644
--- /dev/null
+++ b/m4/expf.m4
@@ -0,0 +1,25 @@
+# expf.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_EXPF],
+[
+  AC_REQUIRE([gl_MATH_H_DEFAULTS])
+  AC_REQUIRE([gl_FUNC_EXP])
+
+  dnl Test whether expf() exists. Assume that expf(), if it exists, is
+  dnl defined in the same library as exp().
+  save_LIBS="$LIBS"
+  LIBS="$LIBS $EXP_LIBM"
+  AC_CHECK_FUNCS([expf])
+  LIBS="$save_LIBS"
+  if test $ac_cv_func_expf = yes; then
+    EXPF_LIBM="$EXP_LIBM"
+  else
+    HAVE_EXPF=0
+    EXPF_LIBM="$EXP_LIBM"
+  fi
+  AC_SUBST([EXPF_LIBM])
+])

--- a/m4/math_h.m4
+++ b/m4/math_h.m4
@@ -1,4 +1,4 @@
-# math_h.m4 serial 32
+# math_h.m4 serial 33
 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 +39,7 @@
   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
+    [acosl asinl atanl ceilf ceill cosl expf expl fabsf floorf floorl fmodf
      frexpf frexpl
      ldexpf ldexpl logb logl modff round roundf roundl sinl sqrtf sqrtl
      tanl trunc truncf truncl])
@@ -63,6 +63,7 @@
   GNULIB_CEILF=0;    AC_SUBST([GNULIB_CEILF])
   GNULIB_CEILL=0;    AC_SUBST([GNULIB_CEILL])
   GNULIB_COSL=0;     AC_SUBST([GNULIB_COSL])
+  GNULIB_EXPF=0;     AC_SUBST([GNULIB_EXPF])
   GNULIB_EXPL=0;     AC_SUBST([GNULIB_EXPL])
   GNULIB_FABSF=0;    AC_SUBST([GNULIB_FABSF])
   GNULIB_FLOOR=0;    AC_SUBST([GNULIB_FLOOR])
@@ -99,6 +100,7 @@
   HAVE_ASINL=1;                AC_SUBST([HAVE_ASINL])
   HAVE_ATANL=1;                AC_SUBST([HAVE_ATANL])
   HAVE_COSL=1;                 AC_SUBST([HAVE_COSL])
+  HAVE_EXPF=1;                 AC_SUBST([HAVE_EXPF])
   HAVE_EXPL=1;                 AC_SUBST([HAVE_EXPL])
   HAVE_FABSF=1;                AC_SUBST([HAVE_FABSF])
   HAVE_FMODF=1;                AC_SUBST([HAVE_FMODF])

new file mode 100644
--- /dev/null
+++ b/modules/expf
@@ -0,0 +1,31 @@
+Description:
+expf() function: exponential function.
+
+Files:
+lib/expf.c
+m4/expf.m4
+
+Depends-on:
+math
+exp             [test $HAVE_EXPF = 0]
+
+configure.ac:
+gl_FUNC_EXPF
+if test $HAVE_EXPF = 0; then
+  AC_LIBOBJ([expf])
+fi
+gl_MATH_MODULE_INDICATOR([expf])
+
+Makefile.am:
+
+Include:
+<math.h>
+
+Link:
+$(EXPF_LIBM)
+
+License:
+LGPL
+
+Maintainer:
+Bruno Haible

--- a/modules/math
+++ b/modules/math
@@ -35,6 +35,7 @@
 	      -e 's/@''GNULIB_CEILF''@/$(GNULIB_CEILF)/g' \
 	      -e 's/@''GNULIB_CEILL''@/$(GNULIB_CEILL)/g' \
 	      -e 's/@''GNULIB_COSL''@/$(GNULIB_COSL)/g' \
+	      -e 's/@''GNULIB_EXPF''@/$(GNULIB_EXPF)/g' \
 	      -e 's/@''GNULIB_EXPL''@/$(GNULIB_EXPL)/g' \
 	      -e 's/@''GNULIB_FABSF''@/$(GNULIB_FABSF)/g' \
 	      -e 's/@''GNULIB_FLOOR''@/$(GNULIB_FLOOR)/g' \
@@ -71,6 +72,7 @@
 	      -e 's|@''HAVE_ASINL''@|$(HAVE_ASINL)|g' \
 	      -e 's|@''HAVE_ATANL''@|$(HAVE_ATANL)|g' \
 	      -e 's|@''HAVE_COSL''@|$(HAVE_COSL)|g' \
+	      -e 's|@''HAVE_EXPF''@|$(HAVE_EXPF)|g' \
 	      -e 's|@''HAVE_EXPL''@|$(HAVE_EXPL)|g' \
 	      -e 's|@''HAVE_FABSF''@|$(HAVE_FABSF)|g' \
 	      -e 's|@''HAVE_FMODF''@|$(HAVE_FMODF)|g' \

--- a/tests/test-math-c++.cc
+++ b/tests/test-math-c++.cc
@@ -34,6 +34,9 @@
 //SIGNATURE_CHECK (GNULIB_NAMESPACE::cosh, double, (double));
 //SIGNATURE_CHECK (GNULIB_NAMESPACE::erf, double, (double));
 //SIGNATURE_CHECK (GNULIB_NAMESPACE::erfc, double, (double));
+#if GNULIB_TEST_EXPF
+SIGNATURE_CHECK (GNULIB_NAMESPACE::expf, float, (float));
+#endif
 //SIGNATURE_CHECK (GNULIB_NAMESPACE::exp, double, (double));
 #if GNULIB_TEST_FABSF
 SIGNATURE_CHECK (GNULIB_NAMESPACE::fabsf, float, (float));