libgfortran/generated/bessel_r8.c

   1 /* Implementation of the BESSEL_JN and BESSEL_YN transformational
   2    function using a recurrence algorithm.
   3    Copyright (C) 2010-2018 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
  29
  30
  31 #define MATHFUNC(funcname) funcname
  32
  33 #if defined (HAVE_GFC_REAL_8)
  34
  35
  36
  37 #if defined (HAVE_JN)
  38 extern void bessel_jn_r8 (gfc_array_r8 * const restrict ret, int n1,
  39                                      int n2, GFC_REAL_8 x);
  40 export_proto(bessel_jn_r8);
  41
  42 void
  43 bessel_jn_r8 (gfc_array_r8 * const restrict ret, int n1, int n2, GFC_REAL_8 x)
  44 {
  45   int i;
  46   index_type stride;
  47
  48   GFC_REAL_8 last1, last2, x2rev;
  49
  50   stride = GFC_DESCRIPTOR_STRIDE(ret,0);
  51
  52   if (ret->base_addr == NULL)
  53     {
  54       size_t size = n2 < n1 ? 0 : n2-n1+1;
  55       GFC_DIMENSION_SET(ret->dim[0], 0, size-1, 1);
  56       ret->base_addr = xmallocarray (size, sizeof (GFC_REAL_8));
  57       ret->offset = 0;
  58     }
  59
  60   if (unlikely (n2 < n1))
  61     return;
  62
  63   if (unlikely (compile_options.bounds_check)
  64       && GFC_DESCRIPTOR_EXTENT(ret,0) != (n2-n1+1))
  65     runtime_error("Incorrect extent in return value of BESSEL_JN "
  66                   "(%ld vs. %ld)", (long int) n2-n1,
  67                   (long int) GFC_DESCRIPTOR_EXTENT(ret,0));
  68
  69   stride = GFC_DESCRIPTOR_STRIDE(ret,0);
  70
  71   if (unlikely (x == 0))
  72     {
  73       ret->base_addr[0] = 1;
  74       for (i = 1; i <= n2-n1; i++)
  75         ret->base_addr[i*stride] = 0;
  76       return;
  77     }
  78
  79   last1 = MATHFUNC(jn) (n2, x);
  80   ret->base_addr[(n2-n1)*stride] = last1;
  81
  82   if (n1 == n2)
  83     return;
  84
  85   last2 = MATHFUNC(jn) (n2 - 1, x);
  86   ret->base_addr[(n2-n1-1)*stride] = last2;
  87
  88   if (n1 + 1 == n2)
  89     return;
  90
  91   x2rev = GFC_REAL_8_LITERAL(2.)/x;
  92
  93   for (i = n2-n1-2; i >= 0; i--)
  94     {
  95       ret->base_addr[i*stride] = x2rev * (i+1+n1) * last2 - last1;
  96       last1 = last2;
  97       last2 = ret->base_addr[i*stride];
  98     }
  99 }
 100
 101 #endif
 102
 103 #if defined (HAVE_YN)
 104 extern void bessel_yn_r8 (gfc_array_r8 * const restrict ret,
 105                                      int n1, int n2, GFC_REAL_8 x);
 106 export_proto(bessel_yn_r8);
 107
 108 void
 109 bessel_yn_r8 (gfc_array_r8 * const restrict ret, int n1, int n2,
 110                          GFC_REAL_8 x)
 111 {
 112   int i;
 113   index_type stride;
 114
 115   GFC_REAL_8 last1, last2, x2rev;
 116
 117   stride = GFC_DESCRIPTOR_STRIDE(ret,0);
 118
 119   if (ret->base_addr == NULL)
 120     {
 121       size_t size = n2 < n1 ? 0 : n2-n1+1;
 122       GFC_DIMENSION_SET(ret->dim[0], 0, size-1, 1);
 123       ret->base_addr = xmallocarray (size, sizeof (GFC_REAL_8));
 124       ret->offset = 0;
 125     }
 126
 127   if (unlikely (n2 < n1))
 128     return;
 129
 130   if (unlikely (compile_options.bounds_check)
 131       && GFC_DESCRIPTOR_EXTENT(ret,0) != (n2-n1+1))
 132     runtime_error("Incorrect extent in return value of BESSEL_JN "
 133                   "(%ld vs. %ld)", (long int) n2-n1,
 134                   (long int) GFC_DESCRIPTOR_EXTENT(ret,0));
 135
 136   stride = GFC_DESCRIPTOR_STRIDE(ret,0);
 137
 138   if (unlikely (x == 0))
 139     {
 140       for (i = 0; i <= n2-n1; i++)
 141 #if defined(GFC_REAL_8_INFINITY)
 142         ret->base_addr[i*stride] = -GFC_REAL_8_INFINITY;
 143 #else
 144         ret->base_addr[i*stride] = -GFC_REAL_8_HUGE;
 145 #endif
 146       return;
 147     }
 148
 149   last1 = MATHFUNC(yn) (n1, x);
 150   ret->base_addr[0] = last1;
 151
 152   if (n1 == n2)
 153     return;
 154
 155   last2 = MATHFUNC(yn) (n1 + 1, x);
 156   ret->base_addr[1*stride] = last2;
 157
 158   if (n1 + 1 == n2)
 159     return;
 160
 161   x2rev = GFC_REAL_8_LITERAL(2.)/x;
 162
 163   for (i = 2; i <= n2 - n1; i++)
 164     {
 165 #if defined(GFC_REAL_8_INFINITY)
 166       if (unlikely (last2 == -GFC_REAL_8_INFINITY))
 167         {
 168           ret->base_addr[i*stride] = -GFC_REAL_8_INFINITY;
 169         }
 170       else
 171 #endif
 172         {
 173           ret->base_addr[i*stride] = x2rev * (i-1+n1) * last2 - last1;
 174           last1 = last2;
 175           last2 = ret->base_addr[i*stride];
 176         }
 177     }
 178 }
 179 #endif
 180
 181 #endif
 182