1/* Implementation of the BESSEL_JN and BESSEL_YN transformational
2   function using a recurrence algorithm.
3   Copyright (C) 2010-2022 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#if defined(GFC_REAL_16_IS_FLOAT128)
32#define MATHFUNC(funcname) funcname ## q
33#else
34#define MATHFUNC(funcname) funcname ## l
35#endif
36
37#if defined (HAVE_GFC_REAL_16)
38
39
40
41#if (defined(GFC_REAL_16_IS_FLOAT128) || defined(HAVE_JNL))
42extern void bessel_jn_r16 (gfc_array_r16 * const restrict ret, int n1,
43				     int n2, GFC_REAL_16 x);
44export_proto(bessel_jn_r16);
45
46void
47bessel_jn_r16 (gfc_array_r16 * const restrict ret, int n1, int n2, GFC_REAL_16 x)
48{
49  int i;
50  index_type stride;
51
52  GFC_REAL_16 last1, last2, x2rev;
53
54  stride = GFC_DESCRIPTOR_STRIDE(ret,0);
55
56  if (ret->base_addr == NULL)
57    {
58      size_t size = n2 < n1 ? 0 : n2-n1+1;
59      GFC_DIMENSION_SET(ret->dim[0], 0, size-1, 1);
60      ret->base_addr = xmallocarray (size, sizeof (GFC_REAL_16));
61      ret->offset = 0;
62    }
63
64  if (unlikely (n2 < n1))
65    return;
66
67  if (unlikely (compile_options.bounds_check)
68      && GFC_DESCRIPTOR_EXTENT(ret,0) != (n2-n1+1))
69    runtime_error("Incorrect extent in return value of BESSEL_JN "
70		  "(%ld vs. %ld)", (long int) n2-n1,
71		  (long int) GFC_DESCRIPTOR_EXTENT(ret,0));
72
73  stride = GFC_DESCRIPTOR_STRIDE(ret,0);
74
75  if (unlikely (x == 0))
76    {
77      ret->base_addr[0] = 1;
78      for (i = 1; i <= n2-n1; i++)
79        ret->base_addr[i*stride] = 0;
80      return;
81    }
82
83  last1 = MATHFUNC(jn) (n2, x);
84  ret->base_addr[(n2-n1)*stride] = last1;
85
86  if (n1 == n2)
87    return;
88
89  last2 = MATHFUNC(jn) (n2 - 1, x);
90  ret->base_addr[(n2-n1-1)*stride] = last2;
91
92  if (n1 + 1 == n2)
93    return;
94
95  x2rev = GFC_REAL_16_LITERAL(2.)/x;
96
97  for (i = n2-n1-2; i >= 0; i--)
98    {
99      ret->base_addr[i*stride] = x2rev * (i+1+n1) * last2 - last1;
100      last1 = last2;
101      last2 = ret->base_addr[i*stride];
102    }
103}
104
105#endif
106
107#if (defined(GFC_REAL_16_IS_FLOAT128) || defined(HAVE_YNL))
108extern void bessel_yn_r16 (gfc_array_r16 * const restrict ret,
109				     int n1, int n2, GFC_REAL_16 x);
110export_proto(bessel_yn_r16);
111
112void
113bessel_yn_r16 (gfc_array_r16 * const restrict ret, int n1, int n2,
114			 GFC_REAL_16 x)
115{
116  int i;
117  index_type stride;
118
119  GFC_REAL_16 last1, last2, x2rev;
120
121  stride = GFC_DESCRIPTOR_STRIDE(ret,0);
122
123  if (ret->base_addr == NULL)
124    {
125      size_t size = n2 < n1 ? 0 : n2-n1+1;
126      GFC_DIMENSION_SET(ret->dim[0], 0, size-1, 1);
127      ret->base_addr = xmallocarray (size, sizeof (GFC_REAL_16));
128      ret->offset = 0;
129    }
130
131  if (unlikely (n2 < n1))
132    return;
133
134  if (unlikely (compile_options.bounds_check)
135      && GFC_DESCRIPTOR_EXTENT(ret,0) != (n2-n1+1))
136    runtime_error("Incorrect extent in return value of BESSEL_JN "
137		  "(%ld vs. %ld)", (long int) n2-n1,
138		  (long int) GFC_DESCRIPTOR_EXTENT(ret,0));
139
140  stride = GFC_DESCRIPTOR_STRIDE(ret,0);
141
142  if (unlikely (x == 0))
143    {
144      for (i = 0; i <= n2-n1; i++)
145#if defined(GFC_REAL_16_INFINITY)
146        ret->base_addr[i*stride] = -GFC_REAL_16_INFINITY;
147#else
148        ret->base_addr[i*stride] = -GFC_REAL_16_HUGE;
149#endif
150      return;
151    }
152
153  last1 = MATHFUNC(yn) (n1, x);
154  ret->base_addr[0] = last1;
155
156  if (n1 == n2)
157    return;
158
159  last2 = MATHFUNC(yn) (n1 + 1, x);
160  ret->base_addr[1*stride] = last2;
161
162  if (n1 + 1 == n2)
163    return;
164
165  x2rev = GFC_REAL_16_LITERAL(2.)/x;
166
167  for (i = 2; i <= n2 - n1; i++)
168    {
169#if defined(GFC_REAL_16_INFINITY)
170      if (unlikely (last2 == -GFC_REAL_16_INFINITY))
171	{
172	  ret->base_addr[i*stride] = -GFC_REAL_16_INFINITY;
173	}
174      else
175#endif
176	{
177	  ret->base_addr[i*stride] = x2rev * (i-1+n1) * last2 - last1;
178	  last1 = last2;
179	  last2 = ret->base_addr[i*stride];
180	}
181    }
182}
183#endif
184
185#endif
186
187