libdspl-2.0/dspl/src/math_std/sinc.c

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/*
* Copyright (c) 2015-2024 Sergey Bakhurin
* Digital Signal Processing Library [http://dsplib.org]
*
* This file is part of DSPL.
*
* 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 3 of the License, or
* (at your option) any later version.
*
* DSPL 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 Foobar. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <stdlib.h>
#include "dspl.h"
#ifdef DOXYGEN_ENGLISH
/*! ****************************************************************************
\ingroup SPEC_MATH_COMMON_GROUP
\brief Function \f$ \textrm{sinc}(x,a) = \frac{\sin(ax)}{ax}\f$
for the real vector `x`.
\param[in] x
Pointer to the input vector \f$ x \f$. \n
Vector size is `[n x 1]`. \n \n
\param[in] n
Input and output vectors size. \n \n
\param[in] a
Function parameter \f$ \textrm{sinc}(x,a) = \frac{\sin(ax)}{ax}\f$. \n\n
\param[out] y
Pointer to the `sinc` function output vector. \n
Vector size is `[n x 1]`. \n
Memory must be allocated. \n \n
\return
`RES_OK` if function calculated successfully. \n
Else \ref ERROR_CODE_GROUP "code error". \n
\author Sergey Bakhurin www.dsplib.org
***************************************************************************** */
#endif
#ifdef DOXYGEN_RUSSIAN
/*! ****************************************************************************
\ingroup SPEC_MATH_COMMON_GROUP
\brief Функция \f$ \textrm{sinc}(x,a) = \frac{\sin(ax)}{ax}\f$.
Функция рассчитывает значения функции для вещественного вектора `x`.
\param[in] x
Указатель на вектор переменной \f$ x \f$. \n
Размер вектора `[n x 1]`. \n
Память должна быть выделена. \n \n
\param[in] n
Размер входного вектора `x`. \n \n
\param[in] a
Параметр функции \f$ \textrm{sinc}(x,a) = \frac{\sin(ax)}{ax}\f$. \n\n
\param[out] y
Указатель на вектор значений функции. \n
Размер вектора `[n x 1]`. \n
Память должна быть выделена. \n \n
\return
`RES_OK` --- расчёт произведен успешно. \n
В противном случае \ref ERROR_CODE_GROUP "код ошибки". \n
\author Бахурин Сергей www.dsplib.org
***************************************************************************** */
#endif
int DSPL_API sinc(double* x, int n, double a, double* y)
{
int k;
if(!x || !y)
return ERROR_PTR;
if(n<1)
return ERROR_SIZE;
for(k = 0; k < n; k++)
y[k] = (x[k]==0.0) ? 1.0 : sin(a*x[k])/(a*x[k]);
return RES_OK;
}