kopia lustrzana https://github.com/Dsplib/libdspl-2.0
163 wiersze
5.0 KiB
C
163 wiersze
5.0 KiB
C
/*
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* Copyright (c) 2015-2020 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 libdspl-2.0.
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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 Lesser 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 Lesser 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 ARRAY_GROUP
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\fn int decimate(double* x, int n, int d, double* y, int* cnt)
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\brief
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Real vector decimation
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Function `d` times decimates real vector `x`. \n
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Output vector `y` keeps values corresponds to:
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`y(k) = x(k*d), k = 0...n/d-1` \n
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\param[in] x
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Pointer to the input real vector `x`. \n
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Vector `x` 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[in] d
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Decimation coefficient. \n
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Each d-th vector will be copy from vector `x` to the
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output vector `y`. \n \n
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\param[out] y
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Pointer to the output decimated vector `y`. \n
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Output vector size is `[n/d x 1]` will be copy
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to the address `cnt`. \n
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\param[out] cnt
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Address which will keep decimated vector `y` size. \n
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Pointer can be `NULL`, vector `y` will not return
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in this case. \n \n
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\return
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`RES_OK` if function calculated successfully. \n
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Else \ref ERROR_CODE_GROUP "code error".
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Two-times decimation example:
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\code{.cpp}
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double x[10] = {0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0};
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double y[5];
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int d = 2;
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int cnt;
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decimate(x, 10, d, y, &cnt);
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\endcode
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As result variable `cnt` will be written value 5 and
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vector `y` will keep array:
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\verbatim
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c = [0.0, 2.0, 4.0, 6.0, 8.0]
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\endverbatim
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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 ARRAY_GROUP
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\fn int decimate(double* x, int n, int d, double* y, int* cnt)
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\brief Децимация вещественного вектора данных
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Функция производит децимацию вещественного вектора `x` в `d` раз. \n
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В результате выходной вектор `y` содержит значения:
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`y(k) = x(k*d), k = 0...n/d-1` \n
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\param[in] x
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Указатель на вектор входных данных `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[in] d
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Коэффициент децимации. \n
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В результате децимации из вектора `x` будет взять каждый
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d-й элемент. \n \n
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\param[out] y
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Указатель на децимированный вектор `y`. \n
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Размер выходного вектора равен `[n/d x 1]`
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будет сохранен по адресу `cnt`. \n
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Память должна быть выделена. \n \n
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\param[out] cnt
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Указатель переменную, в которую будет сохранен
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размер выходного вектора после децимации. \n
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Указатель может быть `NULL`, в этом случае
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размер вектора `y` не возвращается. \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 децимации вещественного массива данных в 2 раза:
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\code{.cpp}
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double x[10] = {0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0};
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double y[5];
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int d = 2;
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int cnt;
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decimate(x, 10, d, y, &cnt);
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\endcode
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В результате в переменную `cnt` будет записан размер 5,
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а вектор `y` будет хранить массив данных:
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\verbatim
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c = [0.0, 2.0, 4.0, 6.0, 8.0]
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\endverbatim
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\author
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Бахурин Сергей
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www.dsplib.org
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**************************************************************************** */
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#endif
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int DSPL_API decimate(double* x, int n, int d, double* y, int* cnt)
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{
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int k = 0, i = 0;
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if(!x || !y)
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return ERROR_PTR;
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if(n < 1)
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return ERROR_SIZE;
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if(d < 1)
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return ERROR_NEGATIVE;
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k = i = 0;
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while(k + d <= n)
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{
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y[i] = x[k];
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k+=d;
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i++;
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}
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if(cnt)
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*cnt = i;
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return RES_OK;
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}
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