1 files changed, 115 insertions, 0 deletions
diff --git a/gsl-1.9/specfunc/atanint.c b/gsl-1.9/specfunc/atanint.c
new file mode 100644
index 0000000..e068929
--- /dev/null
+++ b/gsl-1.9/specfunc/atanint.c
@@ -0,0 +1,115 @@
+/* specfunc/atanint.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_mode.h>
+#include <gsl/gsl_sf_expint.h>
+
+#include "chebyshev.h"
+#include "cheb_eval.c"
+
+
+static double atanint_data[21] = {
+  1.91040361296235937512,
+ -0.4176351437656746940e-01,
+  0.275392550786367434e-02,
+ -0.25051809526248881e-03,
+  0.2666981285121171e-04,
+ -0.311890514107001e-05,
+  0.38833853132249e-06,
+ -0.5057274584964e-07,
+  0.681225282949e-08,
+ -0.94212561654e-09,
+  0.13307878816e-09,
+ -0.1912678075e-10,
+  0.278912620e-11,
+ -0.41174820e-12,
+  0.6142987e-13,
+ -0.924929e-14,
+  0.140387e-14,
+ -0.21460e-15,
+  0.3301e-16,
+ -0.511e-17,
+  0.79e-18,
+};
+static cheb_series atanint_cs = {
+  atanint_data,
+  20,
+  -1, 1,
+  10
+};
+
+
+/*-*-*-*-*-*-*-*-*-*-*-* Functions with Error Codes *-*-*-*-*-*-*-*-*-*-*/
+
+int
+gsl_sf_atanint_e(const double x, gsl_sf_result * result)
+{
+  const double ax  = fabs(x);
+  const double sgn = GSL_SIGN(x);
+
+  /* CHECK_POINTER(result) */
+
+  if(ax == 0.0) {
+    result->val = 0.0;
+    result->err = 0.0;
+    return GSL_SUCCESS;
+  }
+  else if(ax < 0.5*GSL_SQRT_DBL_EPSILON) {
+    result->val = x;
+    result->err = 0.0;
+    return GSL_SUCCESS;
+  }
+  else if(ax <= 1.0) {
+    const double t = 2.0 * (x*x - 0.5);
+    gsl_sf_result result_c;
+    cheb_eval_e(&atanint_cs, t, &result_c);
+    result->val  = x * result_c.val;
+    result->err  = x * result_c.err;
+    result->err += GSL_DBL_EPSILON * fabs(result->val);
+    return GSL_SUCCESS;
+  }
+  else if(ax < 1.0/GSL_SQRT_DBL_EPSILON) {
+    const double t = 2.0 * (1.0/(x*x) - 0.5);
+    gsl_sf_result result_c;
+    cheb_eval_e(&atanint_cs, t, &result_c);
+    result->val  = sgn * (0.5*M_PI*log(ax) + result_c.val/ax);
+    result->err  = result_c.err/ax + fabs(result->val*GSL_DBL_EPSILON);
+    result->err += GSL_DBL_EPSILON * fabs(result->val);
+    return GSL_SUCCESS;
+  }
+  else {
+    result->val = sgn * 0.5*M_PI*log(ax);
+    result->err = 2.0 * fabs(result->val * GSL_DBL_EPSILON);
+    return GSL_SUCCESS;
+  }
+}
+
+/*-*-*-*-*-*-*-*-*-* Functions w/ Natural Prototypes *-*-*-*-*-*-*-*-*-*-*/
+
+#include "eval.h"
+
+double gsl_sf_atanint(const double x)
+{
+  EVAL_RESULT(gsl_sf_atanint_e(x, &result));
+}