182 lines
4.4 KiB
C
182 lines
4.4 KiB
C
/* Implementation of the BESSEL_JN and BESSEL_YN transformational
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function using a recurrence algorithm.
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Copyright (C) 2010-2022 Free Software Foundation, Inc.
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Contributed by Tobias Burnus <burnus@net-b.de>
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This file is part of the GNU Fortran runtime library (libgfortran).
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Libgfortran is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public
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License as published by the Free Software Foundation; either
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version 3 of the License, or (at your option) any later version.
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Libgfortran is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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#include "libgfortran.h"
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#define MATHFUNC(funcname) funcname ## f
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#if defined (HAVE_GFC_REAL_4)
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#if defined (HAVE_JNF)
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extern void bessel_jn_r4 (gfc_array_r4 * const restrict ret, int n1,
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int n2, GFC_REAL_4 x);
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export_proto(bessel_jn_r4);
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void
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bessel_jn_r4 (gfc_array_r4 * const restrict ret, int n1, int n2, GFC_REAL_4 x)
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{
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int i;
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index_type stride;
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GFC_REAL_4 last1, last2, x2rev;
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stride = GFC_DESCRIPTOR_STRIDE(ret,0);
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if (ret->base_addr == NULL)
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{
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size_t size = n2 < n1 ? 0 : n2-n1+1;
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GFC_DIMENSION_SET(ret->dim[0], 0, size-1, 1);
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ret->base_addr = xmallocarray (size, sizeof (GFC_REAL_4));
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ret->offset = 0;
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}
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if (unlikely (n2 < n1))
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return;
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if (unlikely (compile_options.bounds_check)
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&& GFC_DESCRIPTOR_EXTENT(ret,0) != (n2-n1+1))
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runtime_error("Incorrect extent in return value of BESSEL_JN "
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"(%ld vs. %ld)", (long int) n2-n1,
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(long int) GFC_DESCRIPTOR_EXTENT(ret,0));
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stride = GFC_DESCRIPTOR_STRIDE(ret,0);
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if (unlikely (x == 0))
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{
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ret->base_addr[0] = 1;
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for (i = 1; i <= n2-n1; i++)
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ret->base_addr[i*stride] = 0;
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return;
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}
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last1 = MATHFUNC(jn) (n2, x);
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ret->base_addr[(n2-n1)*stride] = last1;
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if (n1 == n2)
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return;
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last2 = MATHFUNC(jn) (n2 - 1, x);
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ret->base_addr[(n2-n1-1)*stride] = last2;
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if (n1 + 1 == n2)
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return;
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x2rev = GFC_REAL_4_LITERAL(2.)/x;
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for (i = n2-n1-2; i >= 0; i--)
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{
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ret->base_addr[i*stride] = x2rev * (i+1+n1) * last2 - last1;
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last1 = last2;
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last2 = ret->base_addr[i*stride];
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}
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}
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#endif
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#if defined (HAVE_YNF)
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extern void bessel_yn_r4 (gfc_array_r4 * const restrict ret,
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int n1, int n2, GFC_REAL_4 x);
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export_proto(bessel_yn_r4);
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void
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bessel_yn_r4 (gfc_array_r4 * const restrict ret, int n1, int n2,
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GFC_REAL_4 x)
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{
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int i;
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index_type stride;
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GFC_REAL_4 last1, last2, x2rev;
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stride = GFC_DESCRIPTOR_STRIDE(ret,0);
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if (ret->base_addr == NULL)
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{
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size_t size = n2 < n1 ? 0 : n2-n1+1;
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GFC_DIMENSION_SET(ret->dim[0], 0, size-1, 1);
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ret->base_addr = xmallocarray (size, sizeof (GFC_REAL_4));
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ret->offset = 0;
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}
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if (unlikely (n2 < n1))
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return;
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if (unlikely (compile_options.bounds_check)
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&& GFC_DESCRIPTOR_EXTENT(ret,0) != (n2-n1+1))
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runtime_error("Incorrect extent in return value of BESSEL_JN "
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"(%ld vs. %ld)", (long int) n2-n1,
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(long int) GFC_DESCRIPTOR_EXTENT(ret,0));
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stride = GFC_DESCRIPTOR_STRIDE(ret,0);
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if (unlikely (x == 0))
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{
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for (i = 0; i <= n2-n1; i++)
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#if defined(GFC_REAL_4_INFINITY)
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ret->base_addr[i*stride] = -GFC_REAL_4_INFINITY;
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#else
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ret->base_addr[i*stride] = -GFC_REAL_4_HUGE;
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#endif
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return;
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}
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last1 = MATHFUNC(yn) (n1, x);
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ret->base_addr[0] = last1;
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if (n1 == n2)
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return;
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last2 = MATHFUNC(yn) (n1 + 1, x);
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ret->base_addr[1*stride] = last2;
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if (n1 + 1 == n2)
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return;
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x2rev = GFC_REAL_4_LITERAL(2.)/x;
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for (i = 2; i <= n2 - n1; i++)
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{
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#if defined(GFC_REAL_4_INFINITY)
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if (unlikely (last2 == -GFC_REAL_4_INFINITY))
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{
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ret->base_addr[i*stride] = -GFC_REAL_4_INFINITY;
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}
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else
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#endif
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{
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ret->base_addr[i*stride] = x2rev * (i-1+n1) * last2 - last1;
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last1 = last2;
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last2 = ret->base_addr[i*stride];
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}
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}
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}
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#endif
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#endif
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