1 files changed, 86 insertions, 0 deletions
diff --git a/gsl-1.9/specfunc/elementary.c b/gsl-1.9/specfunc/elementary.c
new file mode 100644
index 0000000..3d8a36d
--- /dev/null
+++ b/gsl-1.9/specfunc/elementary.c
@@ -0,0 +1,86 @@
+/* specfunc/elementary.c
+ * 
+ * Copyright (C) 1996, 1997, 1998, 1999, 2000 Gerard Jungman
+ * 
+ * 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 2 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+/* Author:  G. Jungman */
+
+#include <config.h>
+#include <gsl/gsl_math.h>
+#include <gsl/gsl_errno.h>
+#include <gsl/gsl_sf_elementary.h>
+
+#include "error.h"
+#include "check.h"
+
+int
+gsl_sf_multiply_e(const double x, const double y, gsl_sf_result * result)
+{
+  const double ax = fabs(x);
+  const double ay = fabs(y);
+
+  if(x == 0.0 || y == 0.0) {
+    /* It is necessary to eliminate this immediately.
+     */
+    result->val = 0.0;
+    result->err = 0.0;
+    return GSL_SUCCESS;
+  }
+  else if((ax <= 1.0 && ay >= 1.0) || (ay <= 1.0 && ax >= 1.0)) {
+    /* Straddling 1.0 is always safe.
+     */
+    result->val = x*y;
+    result->err = 2.0 * GSL_DBL_EPSILON * fabs(result->val);
+    return GSL_SUCCESS;
+  }
+  else {
+    const double f = 1.0 - 2.0 * GSL_DBL_EPSILON;
+    const double min = GSL_MIN_DBL(fabs(x), fabs(y));
+    const double max = GSL_MAX_DBL(fabs(x), fabs(y));
+    if(max < 0.9 * GSL_SQRT_DBL_MAX || min < (f * DBL_MAX)/max) {
+      result->val = GSL_COERCE_DBL(x*y);
+      result->err = 2.0 * GSL_DBL_EPSILON * fabs(result->val);
+      CHECK_UNDERFLOW(result);
+      return GSL_SUCCESS;
+    }
+    else {
+      OVERFLOW_ERROR(result);
+    }
+  }
+}
+
+
+int
+gsl_sf_multiply_err_e(const double x, const double dx,
+                         const double y, const double dy,
+                         gsl_sf_result * result)
+{
+  int status = gsl_sf_multiply_e(x, y, result);
+  result->err += fabs(dx*y) + fabs(dy*x);
+  return status;
+}
+
+
+/*-*-*-*-*-*-*-*-*-* Functions w/ Natural Prototypes *-*-*-*-*-*-*-*-*-*-*/
+
+#include "eval.h"
+
+double gsl_sf_multiply(const double x, const double y)
+{
+  EVAL_RESULT(gsl_sf_multiply_e(x, y, &result));
+}
+