erf function (patch from Bernd Gutmann).

C/arith1.c

@@ -418,6 +418,26 @@ eval1(Int fi, Term t) {
       RERROR();
 #endif
     }
+ case op_erf:
+   {
+     Float dbl = get_float(t), out;
+#if HAVE_ERF
+     out = erf(dbl);
+     RFLOAT(out);
+#else
+     RERROR();
+#endif
+   }
+ case op_erfc:
+   {
+     Float dbl = get_float(t), out;
+#if HAVE_ERF
+     out = erfc(dbl);
+     RFLOAT(out);
+#else
+     RERROR();
+#endif
+   }
     /*
       floor(x) maximum integer greatest or equal to X
 
@@ -814,6 +834,8 @@ static InitUnEntry InitUnTab[] = {
   {"float_integer_part", op_fintp},
   {"sign", op_sign},
   {"lgamma", op_lgamma},
+  {"erf",op_erf},
+  {"erfc",op_erfc},
   {"random", op_random1}
 };
 

H/eval.h

@@ -93,6 +93,8 @@ typedef enum {
   op_fintp,
   op_sign,
   op_lgamma,
+  op_erf,
+  op_erfc,
   op_random1
 } arith1_op;
 

config.h.in

@@ -160,6 +160,7 @@
 #undef  HAVE_CTIME
 #undef  HAVE_DLOPEN
 #undef  HAVE_DUP2
+#undef  HAVE_ERF
 #undef  HAVE_FECLEAREXCEPT
 #undef  HAVE_FESETTRAPENABLE
 #undef  HAVE_FETESTEXCEPT

configure

@@ -8499,12 +8499,14 @@ _ACEOF
 fi
 done
 
-for ac_func in feclearexcept
+for ac_func in erf feclearexcept
 do :
-  ac_fn_c_check_func "$LINENO" "feclearexcept" "ac_cv_func_feclearexcept"
-if test "x$ac_cv_func_feclearexcept" = x""yes; then :
+  as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
+ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
+eval as_val=\$$as_ac_var
+   if test "x$as_val" = x""yes; then :
   cat >>confdefs.h <<_ACEOF
-#define HAVE_FECLEAREXCEPT 1
+#define `$as_echo "HAVE_$ac_func" | $as_tr_cpp` 1
 _ACEOF
 
 fi

configure.in

@@ -1501,7 +1501,7 @@ dnl Checks for library functions.
 AC_TYPE_SIGNAL
 AC_CHECK_FUNCS(access)
 AC_CHECK_FUNCS(acosh asinh atanh chdir ctime dlopen dup2)
-AC_CHECK_FUNCS(feclearexcept)
+AC_CHECK_FUNCS(erf feclearexcept)
 AC_CHECK_FUNCS(fesettrapenable fgetpos finite fpclass ftime getcwd getenv)
 AC_CHECK_FUNCS(gethostbyname gethostid gethostname)
 AC_CHECK_FUNCS(gethrtime getpagesize)

docs/yap.tex

@@ -3849,6 +3849,12 @@ Hyperbolic arc tangent.
 @item lgamma(@var{X})
 gamma function.
 
+@item erf(@var{X})
+gaussian error function.
+
+@item erfc(@var{X})
+complementary gaussian error function.
+
 @item random(@var{X}) [ISO]
 An integer random number between 0 and @var{X}.