1 files changed, 158 insertions, 0 deletions
diff --git a/gsl-1.9/integration/qc25f.c b/gsl-1.9/integration/qc25f.c
new file mode 100644
index 0000000..73c085c
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+++ b/gsl-1.9/integration/qc25f.c
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+/* integration/qc25f.c
+ * 
+ * Copyright (C) 1996, 1997, 1998, 1999, 2000 Brian Gough
+ * 
+ * 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.
+ */
+
+struct fn_fourier_params
+{
+  gsl_function *function;
+  double omega;
+};
+
+static double fn_sin (double t, void *params);
+static double fn_cos (double t, void *params);
+
+static void
+qc25f (gsl_function * f, double a, double b, 
+       gsl_integration_qawo_table * wf, size_t level,
+       double *result, double *abserr, double *resabs, double *resasc);
+
+static void
+qc25f (gsl_function * f, double a, double b, 
+       gsl_integration_qawo_table * wf, size_t level,
+       double *result, double *abserr, double *resabs, double *resasc)
+{
+  const double center = 0.5 * (a + b);
+  const double half_length = 0.5 * (b - a);
+  const double omega = wf->omega ;
+  
+  const double par = omega * half_length;
+
+  if (fabs (par) < 2)
+    {
+      gsl_function weighted_function;
+      struct fn_fourier_params fn_params;
+
+      fn_params.function = f;
+      fn_params.omega = omega;
+
+      if (wf->sine == GSL_INTEG_SINE) 
+        {
+          weighted_function.function = &fn_sin;
+        }
+      else
+        {
+          weighted_function.function = &fn_cos;
+        }
+
+      weighted_function.params = &fn_params;
+
+      gsl_integration_qk15 (&weighted_function, a, b, result, abserr,
+                            resabs, resasc);
+      
+      return;
+    }
+  else
+    {
+      double *moment;
+      double cheb12[13], cheb24[25];
+      double result_abs, res12_cos, res12_sin, res24_cos, res24_sin;
+      double est_cos, est_sin;
+      double c, s;
+      size_t i;
+
+      gsl_integration_qcheb (f, a, b, cheb12, cheb24);
+
+      if (level >= wf->n)
+        {
+          /* table overflow should not happen, check before calling */
+          GSL_ERROR_VOID("table overflow in internal function", GSL_ESANITY);
+        }
+
+      /* obtain moments from the table */
+
+      moment = wf->chebmo + 25 * level;
+
+      res12_cos = cheb12[12] * moment[12];
+      res12_sin = 0 ;
+
+      for (i = 0; i < 6; i++)
+        {
+          size_t k = 10 - 2 * i;
+          res12_cos += cheb12[k] * moment[k];
+          res12_sin += cheb12[k + 1] * moment[k + 1];
+        }
+
+      res24_cos = cheb24[24] * moment[24];
+      res24_sin = 0 ;
+
+      result_abs = fabs(cheb24[24]) ;
+
+      for (i = 0; i < 12; i++)
+        {
+          size_t k = 22 - 2 * i;
+          res24_cos += cheb24[k] * moment[k];
+          res24_sin += cheb24[k + 1] * moment[k + 1];
+          result_abs += fabs(cheb24[k]) + fabs(cheb24[k+1]);
+        }
+
+      est_cos = fabs(res24_cos - res12_cos);
+      est_sin = fabs(res24_sin - res12_sin);
+
+      c = half_length * cos(center * omega);
+      s = half_length * sin(center * omega);
+
+      if (wf->sine == GSL_INTEG_SINE)
+        {
+          *result = c * res24_sin + s * res24_cos;
+          *abserr = fabs(c * est_sin) + fabs(s * est_cos);
+        }
+      else
+        {
+          *result = c * res24_cos - s * res24_sin;
+          *abserr = fabs(c * est_cos) + fabs(s * est_sin);
+        }
+      
+      *resabs = result_abs * half_length;
+      *resasc = GSL_DBL_MAX;
+
+      return;
+    }
+}
+
+static double
+fn_sin (double x, void *params)
+{
+  struct fn_fourier_params *p = (struct fn_fourier_params *) params;
+  gsl_function *f = p->function;
+  double w = p->omega;
+  double wx = w * x;
+  double sinwx = sin(wx) ;
+  return GSL_FN_EVAL (f, x) * sinwx;
+}
+
+static double
+fn_cos (double x, void *params)
+{
+  struct fn_fourier_params *p = (struct fn_fourier_params *) params;
+  gsl_function *f = p->function;
+  double w = p->omega;
+  double wx = w * x;
+  double coswx = cos(wx) ;
+  return GSL_FN_EVAL (f, x) * coswx ;
+}
+