+AC_CHECK_LIB([m],[tanh],[AC_DEFINE([HAVE_TANH],[1],[libm includes tanh])])
+AC_CHECK_LIB([m],[tanhl],[AC_DEFINE([HAVE_TANHL],[1],[libm includes tanhl])])
+AC_CHECK_LIB([m],[ctanhf],[AC_DEFINE([HAVE_CTANHF],[1],[libm includes ctanhf])])
+AC_CHECK_LIB([m],[ctanh],[AC_DEFINE([HAVE_CTANH],[1],[libm includes ctanh])])
+AC_CHECK_LIB([m],[ctanhl],[AC_DEFINE([HAVE_CTANHL],[1],[libm includes ctanhl])])
+AC_CHECK_LIB([m],[truncf],[AC_DEFINE([HAVE_TRUNCF],[1],[libm includes truncf])])
+AC_CHECK_LIB([m],[trunc],[AC_DEFINE([HAVE_TRUNC],[1],[libm includes trunc])])
+AC_CHECK_LIB([m],[truncl],[AC_DEFINE([HAVE_TRUNCL],[1],[libm includes truncl])])
+AC_CHECK_LIB([m],[erff],[AC_DEFINE([HAVE_ERFF],[1],[libm includes erff])])