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1 /* Implementation of the BESSEL_JN and BESSEL_YN transformational
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2 function using a recurrence algorithm.
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145
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3 Copyright (C) 2010-2020 Free Software Foundation, Inc.
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111
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4 Contributed by Tobias Burnus <burnus@net-b.de>
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5
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6 This file is part of the GNU Fortran runtime library (libgfortran).
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7
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8 Libgfortran is free software; you can redistribute it and/or
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9 modify it under the terms of the GNU General Public
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10 License as published by the Free Software Foundation; either
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11 version 3 of the License, or (at your option) any later version.
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12
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13 Libgfortran is distributed in the hope that it will be useful,
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14 but WITHOUT ANY WARRANTY; without even the implied warranty of
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15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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16 GNU General Public License for more details.
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17
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18 Under Section 7 of GPL version 3, you are granted additional
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19 permissions described in the GCC Runtime Library Exception, version
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20 3.1, as published by the Free Software Foundation.
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21
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22 You should have received a copy of the GNU General Public License and
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23 a copy of the GCC Runtime Library Exception along with this program;
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24 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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25 <http://www.gnu.org/licenses/>. */
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26
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27 #include "libgfortran.h"
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28
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29
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30
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31 #define MATHFUNC(funcname) funcname ## f
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32
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33 #if defined (HAVE_GFC_REAL_4)
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34
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35
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36
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37 #if defined (HAVE_JNF)
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38 extern void bessel_jn_r4 (gfc_array_r4 * const restrict ret, int n1,
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39 int n2, GFC_REAL_4 x);
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40 export_proto(bessel_jn_r4);
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41
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42 void
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43 bessel_jn_r4 (gfc_array_r4 * const restrict ret, int n1, int n2, GFC_REAL_4 x)
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44 {
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45 int i;
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46 index_type stride;
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47
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48 GFC_REAL_4 last1, last2, x2rev;
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49
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50 stride = GFC_DESCRIPTOR_STRIDE(ret,0);
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51
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52 if (ret->base_addr == NULL)
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53 {
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54 size_t size = n2 < n1 ? 0 : n2-n1+1;
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55 GFC_DIMENSION_SET(ret->dim[0], 0, size-1, 1);
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56 ret->base_addr = xmallocarray (size, sizeof (GFC_REAL_4));
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57 ret->offset = 0;
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58 }
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59
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60 if (unlikely (n2 < n1))
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61 return;
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62
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63 if (unlikely (compile_options.bounds_check)
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64 && GFC_DESCRIPTOR_EXTENT(ret,0) != (n2-n1+1))
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65 runtime_error("Incorrect extent in return value of BESSEL_JN "
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66 "(%ld vs. %ld)", (long int) n2-n1,
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67 (long int) GFC_DESCRIPTOR_EXTENT(ret,0));
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68
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69 stride = GFC_DESCRIPTOR_STRIDE(ret,0);
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70
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71 if (unlikely (x == 0))
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72 {
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73 ret->base_addr[0] = 1;
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74 for (i = 1; i <= n2-n1; i++)
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75 ret->base_addr[i*stride] = 0;
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76 return;
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77 }
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78
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79 last1 = MATHFUNC(jn) (n2, x);
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80 ret->base_addr[(n2-n1)*stride] = last1;
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81
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82 if (n1 == n2)
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83 return;
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84
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85 last2 = MATHFUNC(jn) (n2 - 1, x);
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86 ret->base_addr[(n2-n1-1)*stride] = last2;
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87
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88 if (n1 + 1 == n2)
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89 return;
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90
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91 x2rev = GFC_REAL_4_LITERAL(2.)/x;
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92
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93 for (i = n2-n1-2; i >= 0; i--)
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94 {
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95 ret->base_addr[i*stride] = x2rev * (i+1+n1) * last2 - last1;
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96 last1 = last2;
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97 last2 = ret->base_addr[i*stride];
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98 }
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99 }
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100
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101 #endif
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102
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103 #if defined (HAVE_YNF)
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104 extern void bessel_yn_r4 (gfc_array_r4 * const restrict ret,
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105 int n1, int n2, GFC_REAL_4 x);
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106 export_proto(bessel_yn_r4);
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107
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108 void
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109 bessel_yn_r4 (gfc_array_r4 * const restrict ret, int n1, int n2,
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110 GFC_REAL_4 x)
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111 {
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112 int i;
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113 index_type stride;
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114
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115 GFC_REAL_4 last1, last2, x2rev;
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116
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117 stride = GFC_DESCRIPTOR_STRIDE(ret,0);
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118
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119 if (ret->base_addr == NULL)
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120 {
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121 size_t size = n2 < n1 ? 0 : n2-n1+1;
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122 GFC_DIMENSION_SET(ret->dim[0], 0, size-1, 1);
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123 ret->base_addr = xmallocarray (size, sizeof (GFC_REAL_4));
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124 ret->offset = 0;
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125 }
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126
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127 if (unlikely (n2 < n1))
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128 return;
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129
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130 if (unlikely (compile_options.bounds_check)
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131 && GFC_DESCRIPTOR_EXTENT(ret,0) != (n2-n1+1))
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132 runtime_error("Incorrect extent in return value of BESSEL_JN "
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133 "(%ld vs. %ld)", (long int) n2-n1,
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134 (long int) GFC_DESCRIPTOR_EXTENT(ret,0));
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135
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136 stride = GFC_DESCRIPTOR_STRIDE(ret,0);
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137
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138 if (unlikely (x == 0))
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139 {
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140 for (i = 0; i <= n2-n1; i++)
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141 #if defined(GFC_REAL_4_INFINITY)
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142 ret->base_addr[i*stride] = -GFC_REAL_4_INFINITY;
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143 #else
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144 ret->base_addr[i*stride] = -GFC_REAL_4_HUGE;
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145 #endif
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146 return;
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147 }
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148
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149 last1 = MATHFUNC(yn) (n1, x);
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150 ret->base_addr[0] = last1;
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151
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152 if (n1 == n2)
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153 return;
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154
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155 last2 = MATHFUNC(yn) (n1 + 1, x);
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156 ret->base_addr[1*stride] = last2;
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157
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158 if (n1 + 1 == n2)
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159 return;
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160
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161 x2rev = GFC_REAL_4_LITERAL(2.)/x;
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162
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163 for (i = 2; i <= n2 - n1; i++)
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164 {
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165 #if defined(GFC_REAL_4_INFINITY)
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166 if (unlikely (last2 == -GFC_REAL_4_INFINITY))
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167 {
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168 ret->base_addr[i*stride] = -GFC_REAL_4_INFINITY;
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169 }
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170 else
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171 #endif
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172 {
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173 ret->base_addr[i*stride] = x2rev * (i-1+n1) * last2 - last1;
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174 last1 = last2;
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175 last2 = ret->base_addr[i*stride];
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176 }
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177 }
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178 }
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179 #endif
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180
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181 #endif
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182
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