273 lines
8.1 KiB
C
273 lines
8.1 KiB
C
<<<<<<< HEAD
|
|
/* ----------------------------------------------------------------------
|
|
* Project: CMSIS DSP Library
|
|
* Title: arm_std_f32.c
|
|
* Description: Standard deviation of the elements of a floating-point vector
|
|
*
|
|
* $Date: 23 April 2021
|
|
* $Revision: V1.9.0
|
|
*
|
|
* Target Processor: Cortex-M and Cortex-A cores
|
|
* -------------------------------------------------------------------- */
|
|
/*
|
|
* Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
|
|
*
|
|
* SPDX-License-Identifier: Apache-2.0
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the License); you may
|
|
* not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an AS IS BASIS, WITHOUT
|
|
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
#include "dsp/statistics_functions.h"
|
|
|
|
/**
|
|
@ingroup groupStats
|
|
*/
|
|
|
|
/**
|
|
@defgroup STD Standard deviation
|
|
|
|
Calculates the standard deviation of the elements in the input vector.
|
|
|
|
The float implementation is relying on arm_var_f32 which is using a two-pass algorithm
|
|
to avoid problem of numerical instabilities and cancellation errors.
|
|
|
|
Fixed point versions are using the standard textbook algorithm since the fixed point
|
|
numerical behavior is different from the float one.
|
|
|
|
Algorithm for fixed point versions is summarized below:
|
|
|
|
|
|
<pre>
|
|
Result = sqrt((sumOfSquares - sum<sup>2</sup> / blockSize) / (blockSize - 1))
|
|
|
|
sumOfSquares = pSrc[0] * pSrc[0] + pSrc[1] * pSrc[1] + ... + pSrc[blockSize-1] * pSrc[blockSize-1]
|
|
sum = pSrc[0] + pSrc[1] + pSrc[2] + ... + pSrc[blockSize-1]
|
|
</pre>
|
|
|
|
There are separate functions for floating point, Q31, and Q15 data types.
|
|
*/
|
|
|
|
/**
|
|
@addtogroup STD
|
|
@{
|
|
*/
|
|
|
|
/**
|
|
@brief Standard deviation of the elements of a floating-point vector.
|
|
@param[in] pSrc points to the input vector
|
|
@param[in] blockSize number of samples in input vector
|
|
@param[out] pResult standard deviation value returned here
|
|
@return none
|
|
*/
|
|
void arm_std_f32(
|
|
const float32_t * pSrc,
|
|
uint32_t blockSize,
|
|
float32_t * pResult)
|
|
{
|
|
float32_t var;
|
|
arm_var_f32(pSrc,blockSize,&var);
|
|
arm_sqrt_f32(var, pResult);
|
|
}
|
|
|
|
/**
|
|
@} end of STD group
|
|
*/
|
|
=======
|
|
/* ----------------------------------------------------------------------
|
|
* Project: CMSIS DSP Library
|
|
* Title: arm_std_f32.c
|
|
* Description: Standard deviation of the elements of a floating-point vector
|
|
*
|
|
* $Date: 27. January 2017
|
|
* $Revision: V.1.5.1
|
|
*
|
|
* Target Processor: Cortex-M cores
|
|
* -------------------------------------------------------------------- */
|
|
/*
|
|
* Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
|
|
*
|
|
* SPDX-License-Identifier: Apache-2.0
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the License); you may
|
|
* not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an AS IS BASIS, WITHOUT
|
|
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
#include "arm_math.h"
|
|
|
|
/**
|
|
* @ingroup groupStats
|
|
*/
|
|
|
|
/**
|
|
* @defgroup STD Standard deviation
|
|
*
|
|
* Calculates the standard deviation of the elements in the input vector.
|
|
* The underlying algorithm is used:
|
|
*
|
|
* <pre>
|
|
* Result = sqrt((sumOfSquares - sum<sup>2</sup> / blockSize) / (blockSize - 1))
|
|
*
|
|
* where, sumOfSquares = pSrc[0] * pSrc[0] + pSrc[1] * pSrc[1] + ... + pSrc[blockSize-1] * pSrc[blockSize-1]
|
|
*
|
|
* sum = pSrc[0] + pSrc[1] + pSrc[2] + ... + pSrc[blockSize-1]
|
|
* </pre>
|
|
*
|
|
* There are separate functions for floating point, Q31, and Q15 data types.
|
|
*/
|
|
|
|
/**
|
|
* @addtogroup STD
|
|
* @{
|
|
*/
|
|
|
|
|
|
/**
|
|
* @brief Standard deviation of the elements of a floating-point vector.
|
|
* @param[in] *pSrc points to the input vector
|
|
* @param[in] blockSize length of the input vector
|
|
* @param[out] *pResult standard deviation value returned here
|
|
* @return none.
|
|
*/
|
|
|
|
void arm_std_f32(
|
|
float32_t * pSrc,
|
|
uint32_t blockSize,
|
|
float32_t * pResult)
|
|
{
|
|
float32_t sum = 0.0f; /* Temporary result storage */
|
|
float32_t sumOfSquares = 0.0f; /* Sum of squares */
|
|
float32_t in; /* input value */
|
|
uint32_t blkCnt; /* loop counter */
|
|
#if defined (ARM_MATH_DSP)
|
|
float32_t meanOfSquares, mean, squareOfMean; /* Temporary variables */
|
|
#else
|
|
float32_t squareOfSum; /* Square of Sum */
|
|
float32_t var; /* Temporary varaince storage */
|
|
#endif
|
|
|
|
if (blockSize == 1U)
|
|
{
|
|
*pResult = 0;
|
|
return;
|
|
}
|
|
|
|
#if defined (ARM_MATH_DSP)
|
|
/* Run the below code for Cortex-M4 and Cortex-M3 */
|
|
|
|
/*loop Unrolling */
|
|
blkCnt = blockSize >> 2U;
|
|
|
|
/* First part of the processing with loop unrolling. Compute 4 outputs at a time.
|
|
** a second loop below computes the remaining 1 to 3 samples. */
|
|
while (blkCnt > 0U)
|
|
{
|
|
/* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
|
|
/* Compute Sum of squares of the input samples
|
|
* and then store the result in a temporary variable, sum. */
|
|
in = *pSrc++;
|
|
sum += in;
|
|
sumOfSquares += in * in;
|
|
in = *pSrc++;
|
|
sum += in;
|
|
sumOfSquares += in * in;
|
|
in = *pSrc++;
|
|
sum += in;
|
|
sumOfSquares += in * in;
|
|
in = *pSrc++;
|
|
sum += in;
|
|
sumOfSquares += in * in;
|
|
|
|
/* Decrement the loop counter */
|
|
blkCnt--;
|
|
}
|
|
|
|
/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
|
|
** No loop unrolling is used. */
|
|
blkCnt = blockSize % 0x4U;
|
|
|
|
while (blkCnt > 0U)
|
|
{
|
|
/* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
|
|
/* Compute Sum of squares of the input samples
|
|
* and then store the result in a temporary variable, sum. */
|
|
in = *pSrc++;
|
|
sum += in;
|
|
sumOfSquares += in * in;
|
|
|
|
/* Decrement the loop counter */
|
|
blkCnt--;
|
|
}
|
|
|
|
/* Compute Mean of squares of the input samples
|
|
* and then store the result in a temporary variable, meanOfSquares. */
|
|
meanOfSquares = sumOfSquares / ((float32_t) blockSize - 1.0f);
|
|
|
|
/* Compute mean of all input values */
|
|
mean = sum / (float32_t) blockSize;
|
|
|
|
/* Compute square of mean */
|
|
squareOfMean = (mean * mean) * (((float32_t) blockSize) /
|
|
((float32_t) blockSize - 1.0f));
|
|
|
|
/* Compute standard deviation and then store the result to the destination */
|
|
arm_sqrt_f32((meanOfSquares - squareOfMean), pResult);
|
|
|
|
#else
|
|
/* Run the below code for Cortex-M0 */
|
|
|
|
/* Loop over blockSize number of values */
|
|
blkCnt = blockSize;
|
|
|
|
while (blkCnt > 0U)
|
|
{
|
|
/* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
|
|
/* Compute Sum of squares of the input samples
|
|
* and then store the result in a temporary variable, sumOfSquares. */
|
|
in = *pSrc++;
|
|
sumOfSquares += in * in;
|
|
|
|
/* C = (A[0] + A[1] + ... + A[blockSize-1]) */
|
|
/* Compute Sum of the input samples
|
|
* and then store the result in a temporary variable, sum. */
|
|
sum += in;
|
|
|
|
/* Decrement the loop counter */
|
|
blkCnt--;
|
|
}
|
|
|
|
/* Compute the square of sum */
|
|
squareOfSum = ((sum * sum) / (float32_t) blockSize);
|
|
|
|
/* Compute the variance */
|
|
var = ((sumOfSquares - squareOfSum) / (float32_t) (blockSize - 1.0f));
|
|
|
|
/* Compute standard deviation and then store the result to the destination */
|
|
arm_sqrt_f32(var, pResult);
|
|
|
|
#endif /* #if defined (ARM_MATH_DSP) */
|
|
}
|
|
|
|
/**
|
|
* @} end of STD group
|
|
*/
|
|
>>>>>>> upper
|