2024-06-16 09:31:13 +00:00
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/* lmath.c
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This file is part of a program that implements a Software-Defined Radio.
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Copyright (C) 2015, 2016, 2023 Warren Pratt, NR0V
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Copyright (C) 2024 Edouard Griffiths, F4EXB Adapted to SDRangel
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program 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 this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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The author can be reached by email at
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warren@wpratt.com
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*/
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#include "comm.hpp"
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#include "lmath.hpp"
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namespace WDSP {
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2024-06-25 01:50:48 +00:00
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void LMath::dR (int n, float* r, float* y, float* z)
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{
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int i, j, k;
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2024-06-25 01:50:48 +00:00
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float alpha, beta, gamma;
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memset (z, 0, (n - 1) * sizeof (float)); // work space
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2024-06-16 09:31:13 +00:00
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y[0] = -r[1];
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alpha = -r[1];
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beta = 1.0;
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for (k = 0; k < n - 1; k++)
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{
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beta *= 1.0 - alpha * alpha;
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gamma = 0.0;
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for (i = k + 1, j = 0; i > 0; i--, j++)
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gamma += r[i] * y[j];
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alpha = - (r[k + 2] + gamma) / beta;
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for (i = 0, j = k; i <= k; i++, j--)
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z[i] = y[i] + alpha * y[j];
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memcpy (y, z, (k + 1) * sizeof (float));
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y[k + 1] = alpha;
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}
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}
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void LMath::trI (
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int n,
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float* r,
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float* B,
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float* y,
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float* v,
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float* dR_z
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)
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{
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int i, j, ni, nj;
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float gamma, t, scale, b;
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memset (y, 0, (n - 1) * sizeof (float)); // work space
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memset (v, 0, (n - 1) * sizeof (float)); // work space
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scale = 1.0 / r[0];
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for (i = 0; i < n; i++)
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r[i] *= scale;
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dR(n - 1, r, y, dR_z);
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t = 0.0;
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for (i = 0; i < n - 1; i++)
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t += r[i + 1] * y[i];
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gamma = 1.0 / (1.0 + t);
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for (i = 0, j = n - 2; i < n - 1; i++, j--)
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v[i] = gamma * y[j];
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B[0] = gamma;
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for (i = 1, j = n - 2; i < n; i++, j--)
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B[i] = v[j];
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for (i = 1; i <= (n - 1) / 2; i++)
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for (j = i; j < n - i; j++)
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B[i * n + j] = B[(i - 1) * n + (j - 1)] + (v[n - j - 1] * v[n - i - 1] - v[i - 1] * v[j - 1]) / gamma;
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for (i = 0; i <= (n - 1)/2; i++)
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for (j = i; j < n - i; j++)
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{
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b = B[i * n + j] *= scale;
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B[j * n + i] = b;
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ni = n - i - 1;
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nj = n - j - 1;
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B[ni * n + nj] = b;
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B[nj * n + ni] = b;
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}
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}
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void LMath::asolve(int xsize, int asize, float* x, float* a, float* r, float* z)
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{
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int i, j, k;
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float beta, alpha, t;
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memset(r, 0, (asize + 1) * sizeof(float)); // work space
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memset(z, 0, (asize + 1) * sizeof(float)); // work space
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for (i = 0; i <= asize; i++)
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{
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for (j = 0; j < xsize; j++)
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r[i] += x[j] * x[j - i];
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}
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z[0] = 1.0;
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beta = r[0];
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for (k = 0; k < asize; k++)
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{
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alpha = 0.0;
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for (j = 0; j <= k; j++)
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alpha -= z[j] * r[k + 1 - j];
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alpha /= beta;
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for (i = 0; i <= (k + 1) / 2; i++)
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{
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t = z[k + 1 - i] + alpha * z[i];
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z[i] = z[i] + alpha * z[k + 1 - i];
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z[k + 1 - i] = t;
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}
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beta *= 1.0 - alpha * alpha;
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}
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for (i = 0; i < asize; i++)
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{
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a[i] = - z[i + 1];
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if (a[i] != a[i]) a[i] = 0.0;
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}
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}
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void LMath::median (int n, float* a, float* med)
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{
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int S0, S1, i, j, m, k;
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float x, t;
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S0 = 0;
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S1 = n - 1;
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k = n / 2;
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while (S1 > S0 + 1)
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{
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m = (S0 + S1) / 2;
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t = a[m];
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a[m] = a[S0 + 1];
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a[S0 + 1] = t;
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if (a[S0] > a[S1])
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{
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t = a[S0];
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a[S0] = a[S1];
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a[S1] = t;
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}
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if (a[S0 + 1] > a[S1])
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{
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t = a[S0 + 1];
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a[S0 + 1] = a[S1];
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a[S1] = t;
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}
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if (a[S0] > a[S0 + 1])
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{
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t = a[S0];
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a[S0] = a[S0 + 1];
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a[S0 + 1] = t;
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}
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i = S0 + 1;
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j = S1;
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x = a[S0 + 1];
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do i++; while (a[i] < x);
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do j--; while (a[j] > x);
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while (j >= i)
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{
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t = a[i];
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a[i] = a[j];
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a[j] = t;
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do i++; while (a[i] < x);
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do j--; while (a[j] > x);
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}
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a[S0 + 1] = a[j];
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a[j] = x;
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if (j >= k) S1 = j - 1;
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if (j <= k) S0 = i;
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}
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if (S1 == S0 + 1 && a[S1] < a[S0])
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{
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t = a[S0];
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a[S0] = a[S1];
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a[S1] = t;
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}
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*med = a[k];
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}
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} // namespace WDSP
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