1/* Implementation of the BESSEL_JN and BESSEL_YN transformational
2   function using a recurrence algorithm.
3   Copyright (C) 2010-2020 Free Software Foundation, Inc.
4   Contributed by Tobias Burnus <burnus@net-b.de>
5
6This file is part of the GNU Fortran runtime library (libgfortran).
7
8Libgfortran is free software; you can redistribute it and/or
9modify it under the terms of the GNU General Public
10License as published by the Free Software Foundation; either
11version 3 of the License, or (at your option) any later version.
12
13Libgfortran is distributed in the hope that it will be useful,
14but WITHOUT ANY WARRANTY; without even the implied warranty of
15MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16GNU General Public License for more details.
17
18Under Section 7 of GPL version 3, you are granted additional
19permissions described in the GCC Runtime Library Exception, version
203.1, as published by the Free Software Foundation.
21
22You should have received a copy of the GNU General Public License and
23a copy of the GCC Runtime Library Exception along with this program;
24see 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 ## l
32
33#if defined (HAVE_GFC_REAL_10)
34
35
36
37#if defined (HAVE_JNL)
38extern void bessel_jn_r10 (gfc_array_r10 * const restrict ret, int n1,
39				     int n2, GFC_REAL_10 x);
40export_proto(bessel_jn_r10);
41
42void
43bessel_jn_r10 (gfc_array_r10 * const restrict ret, int n1, int n2, GFC_REAL_10 x)
44{
45  int i;
46  index_type stride;
47
48  GFC_REAL_10 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_10));
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_10_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_YNL)
104extern void bessel_yn_r10 (gfc_array_r10 * const restrict ret,
105				     int n1, int n2, GFC_REAL_10 x);
106export_proto(bessel_yn_r10);
107
108void
109bessel_yn_r10 (gfc_array_r10 * const restrict ret, int n1, int n2,
110			 GFC_REAL_10 x)
111{
112  int i;
113  index_type stride;
114
115  GFC_REAL_10 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_10));
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_10_INFINITY)
142        ret->base_addr[i*stride] = -GFC_REAL_10_INFINITY;
143#else
144        ret->base_addr[i*stride] = -GFC_REAL_10_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_10_LITERAL(2.)/x;
162
163  for (i = 2; i <= n2 - n1; i++)
164    {
165#if defined(GFC_REAL_10_INFINITY)
166      if (unlikely (last2 == -GFC_REAL_10_INFINITY))
167	{
168	  ret->base_addr[i*stride] = -GFC_REAL_10_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