libgfortran/generated/bessel_r8.c

   1 /* Implementation of the BESSEL_JN and BESSEL_YN transformational
   2    function using a recurrence algorithm.
   3    Copyright (C) 2010-2013 Free Software Foundation, Inc.
   4    Contributed by Tobias Burnus <burnus@net-b.de>
   5
   6 This file is part of the GNU Fortran runtime library (libgfortran).
   7
   8 Libgfortran is free software; you can redistribute it and/or
   9 modify it under the terms of the GNU General Public
  10 License as published by the Free Software Foundation; either
  11 version 3 of the License, or (at your option) any later version.
  12
  13 Libgfortran is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 Under Section 7 of GPL version 3, you are granted additional
  19 permissions described in the GCC Runtime Library Exception, version
  20 3.1, as published by the Free Software Foundation.
  21
  22 You should have received a copy of the GNU General Public License and
  23 a copy of the GCC Runtime Library Exception along with this program;
  24 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  25 <http://www.gnu.org/licenses/>.  */
  26
  27 #include "libgfortran.h"
  28 #include <stdlib.h>
  29 #include <assert.h>
  30
  31
  32
  33 #define MATHFUNC(funcname) funcname
  34
  35 #if defined (HAVE_GFC_REAL_8)
  36
  37
  38
  39 #if defined (HAVE_JN)
  40 extern void bessel_jn_r8 (gfc_array_r8 * const restrict ret, int n1,
  41                                      int n2, GFC_REAL_8 x);
  42 export_proto(bessel_jn_r8);
  43
  44 void
  45 bessel_jn_r8 (gfc_array_r8 * const restrict ret, int n1, int n2, GFC_REAL_8 x)
  46 {
  47   int i;
  48   index_type stride;
  49
  50   GFC_REAL_8 last1, last2, x2rev;
  51
  52   stride = GFC_DESCRIPTOR_STRIDE(ret,0);
  53
  54   if (ret->base_addr == NULL)
  55     {
  56       size_t size = n2 < n1 ? 0 : n2-n1+1;
  57       GFC_DIMENSION_SET(ret->dim[0], 0, size-1, 1);
  58       ret->base_addr = xmalloc (sizeof (GFC_REAL_8) * size);
  59       ret->offset = 0;
  60     }
  61
  62   if (unlikely (n2 < n1))
  63     return;
  64
  65   if (unlikely (compile_options.bounds_check)
  66       && GFC_DESCRIPTOR_EXTENT(ret,0) != (n2-n1+1))
  67     runtime_error("Incorrect extent in return value of BESSEL_JN "
  68                   "(%ld vs. %ld)", (long int) n2-n1,
  69                   (long int) GFC_DESCRIPTOR_EXTENT(ret,0));
  70
  71   stride = GFC_DESCRIPTOR_STRIDE(ret,0);
  72
  73   if (unlikely (x == 0))
  74     {
  75       ret->base_addr[0] = 1;
  76       for (i = 1; i <= n2-n1; i++)
  77         ret->base_addr[i*stride] = 0;
  78       return;
  79     }
  80
  81   last1 = MATHFUNC(jn) (n2, x);
  82   ret->base_addr[(n2-n1)*stride] = last1;
  83
  84   if (n1 == n2)
  85     return;
  86
  87   last2 = MATHFUNC(jn) (n2 - 1, x);
  88   ret->base_addr[(n2-n1-1)*stride] = last2;
  89
  90   if (n1 + 1 == n2)
  91     return;
  92
  93   x2rev = GFC_REAL_8_LITERAL(2.)/x;
  94
  95   for (i = n2-n1-2; i >= 0; i--)
  96     {
  97       ret->base_addr[i*stride] = x2rev * (i+1+n1) * last2 - last1;
  98       last1 = last2;
  99       last2 = ret->base_addr[i*stride];
 100     }
 101 }
 102
 103 #endif
 104
 105 #if defined (HAVE_YN)
 106 extern void bessel_yn_r8 (gfc_array_r8 * const restrict ret,
 107                                      int n1, int n2, GFC_REAL_8 x);
 108 export_proto(bessel_yn_r8);
 109
 110 void
 111 bessel_yn_r8 (gfc_array_r8 * const restrict ret, int n1, int n2,
 112                          GFC_REAL_8 x)
 113 {
 114   int i;
 115   index_type stride;
 116
 117   GFC_REAL_8 last1, last2, x2rev;
 118
 119   stride = GFC_DESCRIPTOR_STRIDE(ret,0);
 120
 121   if (ret->base_addr == NULL)
 122     {
 123       size_t size = n2 < n1 ? 0 : n2-n1+1;
 124       GFC_DIMENSION_SET(ret->dim[0], 0, size-1, 1);
 125       ret->base_addr = xmalloc (sizeof (GFC_REAL_8) * size);
 126       ret->offset = 0;
 127     }
 128
 129   if (unlikely (n2 < n1))
 130     return;
 131
 132   if (unlikely (compile_options.bounds_check)
 133       && GFC_DESCRIPTOR_EXTENT(ret,0) != (n2-n1+1))
 134     runtime_error("Incorrect extent in return value of BESSEL_JN "
 135                   "(%ld vs. %ld)", (long int) n2-n1,
 136                   (long int) GFC_DESCRIPTOR_EXTENT(ret,0));
 137
 138   stride = GFC_DESCRIPTOR_STRIDE(ret,0);
 139
 140   if (unlikely (x == 0))
 141     {
 142       for (i = 0; i <= n2-n1; i++)
 143 #if defined(GFC_REAL_8_INFINITY)
 144         ret->base_addr[i*stride] = -GFC_REAL_8_INFINITY;
 145 #else
 146         ret->base_addr[i*stride] = -GFC_REAL_8_HUGE;
 147 #endif
 148       return;
 149     }
 150
 151   last1 = MATHFUNC(yn) (n1, x);
 152   ret->base_addr[0] = last1;
 153
 154   if (n1 == n2)
 155     return;
 156
 157   last2 = MATHFUNC(yn) (n1 + 1, x);
 158   ret->base_addr[1*stride] = last2;
 159
 160   if (n1 + 1 == n2)
 161     return;
 162
 163   x2rev = GFC_REAL_8_LITERAL(2.)/x;
 164
 165   for (i = 2; i <= n1+n2; i++)
 166     {
 167 #if defined(GFC_REAL_8_INFINITY)
 168       if (unlikely (last2 == -GFC_REAL_8_INFINITY))
 169         {
 170           ret->base_addr[i*stride] = -GFC_REAL_8_INFINITY;
 171         }
 172       else
 173 #endif
 174         {
 175           ret->base_addr[i*stride] = x2rev * (i-1+n1) * last2 - last1;
 176           last1 = last2;
 177           last2 = ret->base_addr[i*stride];
 178         }
 179     }
 180 }
 181 #endif
 182
 183 #endif
 184