Home | History | Annotate | Line # | Download | only in generated 
      1 /* Implementation of the BESSEL_JN and BESSEL_YN transformational
      2    function using a recurrence algorithm.
      3    Copyright (C) 2010-2024 Free Software Foundation, Inc.
      4    Contributed by Tobias Burnus <burnus (at) 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 
    183