1 /* Implementation of the BESSEL_JN and BESSEL_YN transformational
2 function using a recurrence algorithm.
3 Copyright (C) 2010-2023 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 ## f
32
33 #if defined (HAVE_GFC_REAL_4)
34
35
36
37 #if defined (HAVE_JNF)
38 extern void bessel_jn_r4 (gfc_array_r4 * const restrict ret, int n1,
39 int n2, GFC_REAL_4 x);
40 export_proto(bessel_jn_r4);
41
42 void
43 bessel_jn_r4 (gfc_array_r4 * const restrict ret, int n1, int n2, GFC_REAL_4 x)
44 {
45 int i;
46 index_type stride;
47
48 GFC_REAL_4 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_4));
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_4_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_YNF)
104 extern void bessel_yn_r4 (gfc_array_r4 * const restrict ret,
105 int n1, int n2, GFC_REAL_4 x);
106 export_proto(bessel_yn_r4);
107
108 void
109 bessel_yn_r4 (gfc_array_r4 * const restrict ret, int n1, int n2,
110 GFC_REAL_4 x)
111 {
112 int i;
113 index_type stride;
114
115 GFC_REAL_4 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_4));
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_4_INFINITY)
142 ret->base_addr[i*stride] = -GFC_REAL_4_INFINITY;
143 #else
144 ret->base_addr[i*stride] = -GFC_REAL_4_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_4_LITERAL(2.)/x;
162
163 for (i = 2; i <= n2 - n1; i++)
164 {
165 #if defined(GFC_REAL_4_INFINITY)
166 if (unlikely (last2 == -GFC_REAL_4_INFINITY))
167 {
168 ret->base_addr[i*stride] = -GFC_REAL_4_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