kopia lustrzana https://github.com/Dsplib/libdspl-2.0
138 wiersze
4.2 KiB
C
138 wiersze
4.2 KiB
C
/*
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* Copyright (c) 2015-2024 Sergey Bakhurin
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* Digital Signal Processing Library [http://dsplib.org]
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*
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* This file is part of DSPL.
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*
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* 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 3 of the License, or
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* (at your option) any later version.
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*
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* DSPL 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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*
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* You should have received a copy of the GNU General Public License
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* along with Foobar. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "dspl.h"
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#ifdef DOXYGEN_ENGLISH
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/*! ****************************************************************************
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\ingroup SPEC_MATH_STAT_GROUP
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\brief Calculates the standard deviation of the complex input vector `x`
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Function calculates the the standard deviation value
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\f[
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s = \sqrt{\frac{1}{n-1} \sum_{i = 0}^{n-1} \big|x(i) - \mu \big|^2},
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\f]
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here \f$\mu\f$ - mean value of the vector `x`:
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\f[
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\mu = \frac{1}{n} \sum_{i = 0}^{n-1} x(i).
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\f]
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\param[in] x
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Pointer to the complex input vector `x`. \n
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Vector size is `[n x 1]`. \n \n
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\param[in] n
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Size of input vector `x`. \n \n
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\param[out] s
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Pointer to the variable which keeps vector `x` standard deviation value.\n
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Memory must be allocated. \n \n
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`RES_OK` if function calculates successfully,
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else \ref ERROR_CODE_GROUP "code error".
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Example:
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\code{.cpp}
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complex_t a[3] = {{0.0, -1.0}, {1.0, 2.0}, {3.0, 5.0}};
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double s;
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stat_std_cmplx(a, 3, &s);
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printf("\n\n Standard deviation value: %8.1f\n", s);
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\endcode
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As result the variable `s` will keep value `3.3665`.
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\author Sergey Bakhurin www.dsplib.org
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***************************************************************************** */
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#endif
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#ifdef DOXYGEN_RUSSIAN
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/*! ****************************************************************************
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\ingroup SPEC_MATH_STAT_GROUP
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\brief Выборочная оценка стандартного отклонения комплексного вектора `x`
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Функция рассчитывает оценку стандартного отклонения
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\f[
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s = \sqrt{\frac{1}{n-1} \sum_{i = 0}^{n-1} \big|x(i) - \mu \big|^2},
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\f]
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где \f$\mu\f$ - выборочная оценка математического ожидания вектора `x`:
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\f[
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\mu = \frac{1}{n} \sum_{i = 0}^{n-1} x(i).
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\f]
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\note Для комплексного вектора данных, величина стандартного отклонения
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всегда вещественная и неотрицательная.
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\param[in] x
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Указатель на комплексный вектор `x`. \n
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Размер вектора `[n x 1]`. \n \n
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\param[in] n
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Размер входного вектора `x`. \n \n
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\param[out] s
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Указатель на адрес памяти, в который сохранить
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рассчитанное значение стандартного отклонения вектора `x`. \n
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Память должна быть выделена. \n \n
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\return
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`RES_OK` если функция выполнена успешно. \n
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В противном случае \ref ERROR_CODE_GROUP "код ошибки".
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Пример:
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\code{.cpp}
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complex_t a[3] = {{0.0, -1.0}, {1.0, 2.0}, {3.0, 5.0}};
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double s;
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stat_std_cmplx(a, 3, &s);
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printf("\n\n Standard deviation value: %8.1f\n", s);
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\endcode
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В результате в переменную `s` будет записано значение `3.3665`.
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\author Бахурин Сергей. www.dsplib.org
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***************************************************************************** */
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#endif
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int DSPL_API stat_std_cmplx(complex_t* x, int n, double* s)
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{
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int k, err;
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complex_t tmp, m;
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double sum;
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err = mean_cmplx(x, n, &m);
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if(err != RES_OK)
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goto exit_label;
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sum = 0.0;
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for(k = 0; k < n; k++)
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{
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RE(tmp) = RE(x[k]) - RE(m);
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IM(tmp) = IM(x[k]) - IM(m);
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sum += ABSSQR(tmp);
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}
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*s = sqrt(sum / (double)(n-1));
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exit_label:
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return err;
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}
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