2 dnl Copyright (C) 2010 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
7 AC_DEFUN([gl_FUNC_LOGB],
9 AC_REQUIRE([gl_MATH_H_DEFAULTS])
10 dnl Test whether logb() is declared.
11 AC_CHECK_DECLS([logb], , , [#include <math.h>])
12 if test "$ac_cv_have_decl_logb" != yes; then
15 dnl Test whether logb() can be used without libm.
18 #ifndef __NO_MATH_INLINES
19 # define __NO_MATH_INLINES 1 /* for glibc */
22 extern double logb (double x);
26 if test "$LOGB_LIBM" = "?"; then
30 #ifndef __NO_MATH_INLINES
31 # define __NO_MATH_INLINES 1 /* for glibc */
34 extern double logb (double x);
40 if test "$LOGB_LIBM" = "?"; then