mirror of
https://github.com/vale981/arb
synced 2025-03-05 17:31:38 -05:00
131 lines
3.4 KiB
C
131 lines
3.4 KiB
C
/*=============================================================================
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This file is part of ARB.
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ARB is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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ARB 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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You should have received a copy of the GNU General Public License
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along with ARB; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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=============================================================================*/
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/******************************************************************************
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Copyright (C) 2016 Pascal Molin
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******************************************************************************/
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#include "acb_dirichlet.h"
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/* shallow copy */
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static acb_ptr
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vec_extract(acb_srcptr v, slong step, slong len)
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{
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slong k;
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acb_ptr res;
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res = flint_malloc(len * sizeof(acb_struct));
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for (k = 0; k < len; k++)
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{
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res[k] = v[0];
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v += step;
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}
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return res;
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}
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void
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_acb_dft_base(acb_ptr w, acb_srcptr v, slong dv, acb_srcptr z, slong dz, slong n, slong prec)
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{
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acb_ptr v1, z1;
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v1 = vec_extract(v, dv, n);
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z1 = vec_extract(z, dz, n);
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_acb_dirichlet_dft_pol(w, v1, z1, n, prec);
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flint_free(v1);
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flint_free(z1);
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}
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typedef struct
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{
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slong num;
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slong n;
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slong * m;
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slong * M;
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acb_ptr z;
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}
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acb_dft_struct;
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typedef acb_dft_struct acb_dft_t[1];
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void
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_acb_dft_fast(acb_ptr w, acb_srcptr v, slong dv, acb_srcptr z, slong dz, slong * cyc, slong * cocyc, slong num, slong prec)
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{
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if (num == 1)
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{
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_acb_dft_base(w, v, dv, z, dz, cyc[0], prec);
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}
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else
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{
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slong i, j, m, M;
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acb_ptr t, wi;
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m = cyc[0];
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M = cocyc[0];
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t = _acb_vec_init(m * M);
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wi = w;
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for (i = 0; i < m; i++)
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{
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_acb_dft_fast(wi, v + i * dv, m * dv, z, dz * m, cyc + 1, cocyc + 1, num - 1, prec);
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if (i)
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{
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for (j = 1; j < M; j++)
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acb_mul(wi + j, wi + j, z + dz * i * j, prec);
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}
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wi += M;
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}
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/* after first pass */
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for (j = 0; j < M; j++)
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_acb_dft_base(t + m * j, w + j, M, z, dz * M, m, prec);
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/* reorder */
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for (i = 0; i < m; i++)
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for (j = 0; j < M; j++)
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w[j + M * i] = t[i + m * j];
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_acb_vec_clear(t, m * M);
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}
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}
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void
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acb_dirichlet_dft_fast(acb_ptr w, acb_srcptr v, slong len, slong prec)
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{
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slong i, j, num;
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n_factor_t fac;
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slong * cyc, * cocyc;
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acb_ptr z;
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z = acb_roots_init(len, prec);
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n_factor_init(&fac);
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n_factor(&fac, len, 0);
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num = 0;
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for (i = 0; i < fac.num; i++)
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num += fac.exp[i];
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cyc = flint_malloc(num * sizeof(slong));
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cocyc = flint_malloc(num * sizeof(slong));
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num = 0;
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for (i = 0; i < fac.num; i++)
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{
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for (j = 0; j < fac.exp[i]; j++)
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{
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cyc[num] = fac.p[i];
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cocyc[num] = (len /= cyc[num]);
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num++;
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}
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}
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_acb_dft_fast(w, v, 1, z, 1, cyc, cocyc, num, prec);
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}
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