--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2011-10-10  Bruno Haible  <bruno@clisp.org>
+
+	expl: Simplify for platforms where 'long double' == 'double'.
+	* lib/expl.c (expl) [HAVE_SAME_LONG_DOUBLE_AS_DOUBLE]: New alternative
+	implementation.
+	* m4/expl.m4 (gl_FUNC_EXPL): Require gl_LONG_DOUBLE_VS_DOUBLE.
+	Determine EXPL_LIBM according to HAVE_SAME_LONG_DOUBLE_AS_DOUBLE.
+	* modules/expl (Depends-on): Add exp. Update conditions.
+
 2011-10-10  Bruno Haible  <bruno@clisp.org>
 
 	sqrtl: Simplify for platforms where 'long double' == 'double'.

--- a/lib/expl.c
+++ b/lib/expl.c
@@ -23,16 +23,26 @@
 /* Specification.  */
 #include <math.h>
 
-#include <float.h>
+#if HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
+
+long double
+expl (long double x)
+{
+  return exp (x);
+}
+
+#else
+
+# include <float.h>
 
 static const long double C[] = {
 /* Chebyshev polynom coeficients for (exp(x)-1)/x */
-#define P1 C[0]
-#define P2 C[1]
-#define P3 C[2]
-#define P4 C[3]
-#define P5 C[4]
-#define P6 C[5]
+# define P1 C[0]
+# define P2 C[1]
+# define P3 C[2]
+# define P4 C[3]
+# define P5 C[4]
+# define P6 C[5]
  0.5L,
  1.66666666666666666666666666666666683E-01L,
  4.16666666666666666666654902320001674E-02L,
@@ -41,19 +51,19 @@
  1.98412698413981650382436541785404286E-04L,
 
 /* Smallest integer x for which e^x overflows.  */
-#define himark C[6]
+# define himark C[6]
  11356.523406294143949491931077970765L,
 
 /* Largest integer x for which e^x underflows.  */
-#define lomark C[7]
+# define lomark C[7]
 -11433.4627433362978788372438434526231L,
 
 /* very small number */
-#define TINY C[8]
+# define TINY C[8]
  1.0e-4900L,
 
 /* 2^16383 */
-#define TWO16383 C[9]
+# define TWO16383 C[9]
  5.94865747678615882542879663314003565E+4931L};
 
 long double
@@ -118,6 +128,8 @@
     return TWO16383*x;
 }
 
+#endif
+
 #if 0
 int
 main (void)

--- a/m4/expl.m4
+++ b/m4/expl.m4
@@ -1,4 +1,4 @@
-# expl.m4 serial 4
+# expl.m4 serial 5
 dnl Copyright (C) 2010-2011 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -7,6 +7,8 @@
 AC_DEFUN([gl_FUNC_EXPL],
 [
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
+  AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
+
   dnl Persuade glibc <math.h> to declare expl().
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
 
@@ -56,8 +58,13 @@
     HAVE_DECL_EXPL=0
     HAVE_EXPL=0
     dnl Find libraries needed to link lib/expl.c.
-    AC_REQUIRE([gl_FUNC_FLOORL])
-    EXPL_LIBM="$FLOORL_LIBM"
+    if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then
+      AC_REQUIRE([gl_FUNC_EXP])
+      EXPL_LIBM="$EXP_LIBM"
+    else
+      AC_REQUIRE([gl_FUNC_FLOORL])
+      EXPL_LIBM="$FLOORL_LIBM"
+    fi
   fi
   AC_SUBST([EXPL_LIBM])
 ])

--- a/modules/expl
+++ b/modules/expl
@@ -8,8 +8,9 @@
 Depends-on:
 math
 extensions
-float           [test $HAVE_EXPL = 0]
-floorl          [test $HAVE_EXPL = 0]
+exp             [test $HAVE_EXPL = 0 && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1]
+float           [test $HAVE_EXPL = 0 && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 0]
+floorl          [test $HAVE_EXPL = 0 && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 0]
 
 configure.ac:
 gl_FUNC_EXPL