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sdrangel/wdsp/lmath.cpp
f4exb 7be39b1b55 WDSP: use double internally for SNBA
2024-07-11 21:25:52 +02:00

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/* lmath.c
This file is part of a program that implements a Software-Defined Radio.
Copyright (C) 2015, 2016, 2023 Warren Pratt, NR0V
Copyright (C) 2024 Edouard Griffiths, F4EXB Adapted to SDRangel
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
The author can be reached by email at
warren@wpratt.com
*/
#include "comm.hpp"
#include "lmath.hpp"
namespace WDSP {
void LMath::dR (int n, float* r, float* y, float* z)
{
int i, j, k;
float alpha, beta, gamma;
memset (z, 0, (n - 1) * sizeof (float)); // work space
y[0] = -r[1];
alpha = -r[1];
beta = 1.0;
for (k = 0; k < n - 1; k++)
{
beta *= 1.0 - alpha * alpha;
gamma = 0.0;
for (i = k + 1, j = 0; i > 0; i--, j++)
gamma += r[i] * y[j];
alpha = - (r[k + 2] + gamma) / beta;
for (i = 0, j = k; i <= k; i++, j--)
z[i] = y[i] + alpha * y[j];
memcpy (y, z, (k + 1) * sizeof (float));
y[k + 1] = alpha;
}
}
void LMathd::dR (int n, double* r, double* y, double* z)
{
int i, j, k;
double alpha, beta, gamma;
memset (z, 0, (n - 1) * sizeof (double)); // work space
y[0] = -r[1];
alpha = -r[1];
beta = 1.0;
for (k = 0; k < n - 1; k++)
{
beta *= 1.0 - alpha * alpha;
gamma = 0.0;
for (i = k + 1, j = 0; i > 0; i--, j++)
gamma += r[i] * y[j];
alpha = - (r[k + 2] + gamma) / beta;
for (i = 0, j = k; i <= k; i++, j--)
z[i] = y[i] + alpha * y[j];
memcpy (y, z, (k + 1) * sizeof (double));
y[k + 1] = alpha;
}
}
void LMath::trI (
int n,
float* r,
float* B,
float* y,
float* v,
float* dR_z
)
{
int i, j, ni, nj;
float gamma, t, scale, b;
memset (y, 0, (n - 1) * sizeof (float)); // work space
memset (v, 0, (n - 1) * sizeof (float)); // work space
scale = 1.0 / r[0];
for (i = 0; i < n; i++)
r[i] *= scale;
dR(n - 1, r, y, dR_z);
t = 0.0;
for (i = 0; i < n - 1; i++)
t += r[i + 1] * y[i];
gamma = 1.0 / (1.0 + t);
for (i = 0, j = n - 2; i < n - 1; i++, j--)
v[i] = gamma * y[j];
B[0] = gamma;
for (i = 1, j = n - 2; i < n; i++, j--)
B[i] = v[j];
for (i = 1; i <= (n - 1) / 2; i++)
for (j = i; j < n - i; j++)
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;
for (i = 0; i <= (n - 1)/2; i++)
for (j = i; j < n - i; j++)
{
b = B[i * n + j] *= scale;
B[j * n + i] = b;
ni = n - i - 1;
nj = n - j - 1;
B[ni * n + nj] = b;
B[nj * n + ni] = b;
}
}
void LMathd::trI (
int n,
double* r,
double* B,
double* y,
double* v,
double* dR_z
)
{
int i, j, ni, nj;
double gamma, t, scale, b;
memset (y, 0, (n - 1) * sizeof (double)); // work space
memset (v, 0, (n - 1) * sizeof (double)); // work space
scale = 1.0 / r[0];
for (i = 0; i < n; i++)
r[i] *= scale;
dR(n - 1, r, y, dR_z);
t = 0.0;
for (i = 0; i < n - 1; i++)
t += r[i + 1] * y[i];
gamma = 1.0 / (1.0 + t);
for (i = 0, j = n - 2; i < n - 1; i++, j--)
v[i] = gamma * y[j];
B[0] = gamma;
for (i = 1, j = n - 2; i < n; i++, j--)
B[i] = v[j];
for (i = 1; i <= (n - 1) / 2; i++)
for (j = i; j < n - i; j++)
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;
for (i = 0; i <= (n - 1)/2; i++)
for (j = i; j < n - i; j++)
{
b = B[i * n + j] *= scale;
B[j * n + i] = b;
ni = n - i - 1;
nj = n - j - 1;
B[ni * n + nj] = b;
B[nj * n + ni] = b;
}
}
void LMath::asolve(int xsize, int asize, float* x, float* a, float* r, float* z)
{
int i, j, k;
float beta, alpha, t;
memset(r, 0, (asize + 1) * sizeof(float)); // work space
memset(z, 0, (asize + 1) * sizeof(float)); // work space
for (i = 0; i <= asize; i++)
{
for (j = 0; j < xsize; j++)
r[i] += x[j] * x[j - i];
}
z[0] = 1.0;
beta = r[0];
for (k = 0; k < asize; k++)
{
alpha = 0.0;
for (j = 0; j <= k; j++)
alpha -= z[j] * r[k + 1 - j];
alpha /= beta;
for (i = 0; i <= (k + 1) / 2; i++)
{
t = z[k + 1 - i] + alpha * z[i];
z[i] = z[i] + alpha * z[k + 1 - i];
z[k + 1 - i] = t;
}
beta *= 1.0 - alpha * alpha;
}
for (i = 0; i < asize; i++)
{
a[i] = - z[i + 1];
if (a[i] != a[i]) a[i] = 0.0;
}
}
void LMathd::asolve(int xsize, int asize, double* x, double* a, double* r, double* z)
{
int i, j, k;
double beta, alpha, t;
memset(r, 0, (asize + 1) * sizeof(double)); // work space
memset(z, 0, (asize + 1) * sizeof(double)); // work space
for (i = 0; i <= asize; i++)
{
for (j = 0; j < xsize; j++)
r[i] += x[j] * x[j - i];
}
z[0] = 1.0;
beta = r[0];
for (k = 0; k < asize; k++)
{
alpha = 0.0;
for (j = 0; j <= k; j++)
alpha -= z[j] * r[k + 1 - j];
alpha /= beta;
for (i = 0; i <= (k + 1) / 2; i++)
{
t = z[k + 1 - i] + alpha * z[i];
z[i] = z[i] + alpha * z[k + 1 - i];
z[k + 1 - i] = t;
}
beta *= 1.0 - alpha * alpha;
}
for (i = 0; i < asize; i++)
{
a[i] = - z[i + 1];
if (a[i] != a[i]) a[i] = 0.0;
}
}
void LMath::median (int n, float* a, float* med)
{
int S0, S1, i, j, m, k;
float x, t;
S0 = 0;
S1 = n - 1;
k = n / 2;
while (S1 > S0 + 1)
{
m = (S0 + S1) / 2;
t = a[m];
a[m] = a[S0 + 1];
a[S0 + 1] = t;
if (a[S0] > a[S1])
{
t = a[S0];
a[S0] = a[S1];
a[S1] = t;
}
if (a[S0 + 1] > a[S1])
{
t = a[S0 + 1];
a[S0 + 1] = a[S1];
a[S1] = t;
}
if (a[S0] > a[S0 + 1])
{
t = a[S0];
a[S0] = a[S0 + 1];
a[S0 + 1] = t;
}
i = S0 + 1;
j = S1;
x = a[S0 + 1];
do i++; while (a[i] < x);
do j--; while (a[j] > x);
while (j >= i)
{
t = a[i];
a[i] = a[j];
a[j] = t;
do i++; while (a[i] < x);
do j--; while (a[j] > x);
}
a[S0 + 1] = a[j];
a[j] = x;
if (j >= k) S1 = j - 1;
if (j <= k) S0 = i;
}
if (S1 == S0 + 1 && a[S1] < a[S0])
{
t = a[S0];
a[S0] = a[S1];
a[S1] = t;
}
*med = a[k];
}
void LMathd::median (int n, double* a, double* med)
{
int S0, S1, i, j, m, k;
double x, t;
S0 = 0;
S1 = n - 1;
k = n / 2;
while (S1 > S0 + 1)
{
m = (S0 + S1) / 2;
t = a[m];
a[m] = a[S0 + 1];
a[S0 + 1] = t;
if (a[S0] > a[S1])
{
t = a[S0];
a[S0] = a[S1];
a[S1] = t;
}
if (a[S0 + 1] > a[S1])
{
t = a[S0 + 1];
a[S0 + 1] = a[S1];
a[S1] = t;
}
if (a[S0] > a[S0 + 1])
{
t = a[S0];
a[S0] = a[S0 + 1];
a[S0 + 1] = t;
}
i = S0 + 1;
j = S1;
x = a[S0 + 1];
do i++; while (a[i] < x);
do j--; while (a[j] > x);
while (j >= i)
{
t = a[i];
a[i] = a[j];
a[j] = t;
do i++; while (a[i] < x);
do j--; while (a[j] > x);
}
a[S0 + 1] = a[j];
a[j] = x;
if (j >= k) S1 = j - 1;
if (j <= k) S0 = i;
}
if (S1 == S0 + 1 && a[S1] < a[S0])
{
t = a[S0];
a[S0] = a[S1];
a[S1] = t;
}
*med = a[k];
}
} // namespace WDSP
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