1 files changed, 122 insertions, 0 deletions
diff --git a/gsl-1.9/specfunc/bessel_Inu.c b/gsl-1.9/specfunc/bessel_Inu.c
new file mode 100644
index 0000000..aa6d06a
--- /dev/null
+++ b/gsl-1.9/specfunc/bessel_Inu.c
@@ -0,0 +1,122 @@
+/* specfunc/bessel_Inu.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_exp.h>
+#include <gsl/gsl_sf_gamma.h>
+#include <gsl/gsl_sf_bessel.h>
+
+#include "error.h"
+
+#include "bessel.h"
+#include "bessel_temme.h"
+
+
+/*-*-*-*-*-*-*-*-*-*-*-* Functions with Error Codes *-*-*-*-*-*-*-*-*-*-*-*/
+
+int
+gsl_sf_bessel_Inu_scaled_e(double nu, double x, gsl_sf_result * result)
+{
+  /* CHECK_POINTER(result) */
+
+  if(x < 0.0 || nu < 0.0) {
+    DOMAIN_ERROR(result);
+  }
+  else if(x*x < 10.0*(nu+1.0)) {
+    gsl_sf_result b;
+    double ex = exp(-x);
+    int stat = gsl_sf_bessel_IJ_taylor_e(nu, x, 1, 100, GSL_DBL_EPSILON, &b);
+    result->val  = b.val * ex;
+    result->err  = b.err * ex;
+    result->err += 2.0 * GSL_DBL_EPSILON * fabs(result->val);
+    return stat;
+  }
+  else if(0.5/(nu*nu + x*x) < GSL_ROOT3_DBL_EPSILON) {
+    return gsl_sf_bessel_Inu_scaled_asymp_unif_e(nu, x, result);
+  }
+  else {
+    int N = (int)(nu + 0.5);
+    double mu = nu - N;      /* -1/2 <= mu <= 1/2 */ 
+    double K_mu, K_mup1, Kp_mu;
+    double K_nu, K_nup1, K_num1;
+    double I_nu_ratio;
+    int stat_Irat;
+    int stat_Kmu;
+    int n;
+
+    /* obtain K_mu, K_mup1 */
+    if(x < 2.0) {
+      stat_Kmu = gsl_sf_bessel_K_scaled_temme(mu, x, &K_mu, &K_mup1, &Kp_mu);
+    }
+    else {
+      stat_Kmu = gsl_sf_bessel_K_scaled_steed_temme_CF2(mu, x, &K_mu, &K_mup1, &Kp_mu);
+    }
+
+    /* recurse forward to obtain K_num1, K_nu */
+    K_nu   = K_mu;
+    K_nup1 = K_mup1;
+
+    for(n=0; n<N; n++) {
+      K_num1 = K_nu;
+      K_nu   = K_nup1;
+      K_nup1 = 2.0*(mu+n+1)/x * K_nu + K_num1;
+    }
+
+    /* calculate I_{nu+1}/I_nu */
+    stat_Irat = gsl_sf_bessel_I_CF1_ser(nu, x, &I_nu_ratio);
+
+    /* solve for I_nu */
+    result->val = 1.0/(x * (K_nup1 + I_nu_ratio * K_nu));
+    result->err = GSL_DBL_EPSILON * (0.5*N + 2.0) * fabs(result->val);
+
+    return GSL_ERROR_SELECT_2(stat_Kmu, stat_Irat);
+  }
+}
+
+
+int
+gsl_sf_bessel_Inu_e(double nu, double x, gsl_sf_result * result)
+{
+  gsl_sf_result b;
+  int stat_I = gsl_sf_bessel_Inu_scaled_e(nu, x, &b);
+  int stat_e = gsl_sf_exp_mult_err_e(x, fabs(x*GSL_DBL_EPSILON),
+                                        b.val, b.err,
+                                        result);
+  return GSL_ERROR_SELECT_2(stat_e, stat_I);
+}
+
+
+/*-*-*-*-*-*-*-*-*-* Functions w/ Natural Prototypes *-*-*-*-*-*-*-*-*-*-*/
+
+#include "eval.h"
+
+double gsl_sf_bessel_Inu_scaled(double nu, double x)
+{
+  EVAL_RESULT(gsl_sf_bessel_Inu_scaled_e(nu, x, &result));
+}
+
+
+double gsl_sf_bessel_Inu(double nu, double x)
+{
+  EVAL_RESULT(gsl_sf_bessel_Inu_e(nu, x, &result));
+}