+++ /dev/null
-/* ----------------------------------------------------------------------
-* Copyright (C) 2010 ARM Limited. All rights reserved.
-*
-* $Date: 15. July 2011
-* $Revision: V1.0.10
-*
-* Project: CMSIS DSP Library
-* Title: arm_var_f32.c
-*
-* Description: Variance of the elements of a floating-point vector.
-*
-* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
-*
-* Version 1.0.10 2011/7/15
-* Big Endian support added and Merged M0 and M3/M4 Source code.
-*
-* Version 1.0.3 2010/11/29
-* Re-organized the CMSIS folders and updated documentation.
-*
-* Version 1.0.2 2010/11/11
-* Documentation updated.
-*
-* Version 1.0.1 2010/10/05
-* Production release and review comments incorporated.
-*
-* Version 1.0.0 2010/09/20
-* Production release and review comments incorporated.
-* ---------------------------------------------------------------------------- */
-
-#include "arm_math.h"
-
-/**
- * @ingroup groupStats
- */
-
-/**
- * @defgroup variance Variance
- *
- * Calculates the variance of the elements in the input vector.
- * The underlying algorithm is used:
- *
- * <pre>
- * Result = (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 variance
- * @{
- */
-
-
-/**
- * @brief Variance 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 variance value returned here
- * @return none.
- *
- */
-
-
-void arm_var_f32(
- float32_t * pSrc,
- uint32_t blockSize,
- float32_t * pResult)
-{
-
-#ifndef ARM_MATH_CM0
-
- /* Run the below code for Cortex-M4 and Cortex-M3 */
-
- float32_t sum = (float32_t) 0.0; /* Accumulator */
- float32_t meanOfSquares, mean, in, squareOfMean; /* Temporary variables */
- uint32_t blkCnt; /* loop counter */
- float32_t *pIn; /* Temporary pointer */
-
- /* updating temporary pointer */
- pIn = pSrc;
-
- /*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 * in;
- in = *pSrc++;
- sum += in * in;
- in = *pSrc++;
- sum += in * in;
- in = *pSrc++;
- sum += 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 * 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 = sum / ((float32_t) blockSize - 1.0f);
-
- /* Reset the accumulator */
- sum = 0.0f;
-
- /*loop Unrolling */
- blkCnt = blockSize >> 2u;
-
- /* Reset the input working pointer */
- pSrc = pIn;
-
- /* 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[1] + A[2] + ... + A[blockSize-1]) */
- /* Compute sum of all input values and then store the result in a temporary variable, sum. */
- sum += *pSrc++;
- sum += *pSrc++;
- sum += *pSrc++;
- sum += *pSrc++;
-
- /* 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[1] + A[2] + ... + A[blockSize-1]) */
- /* Compute sum of all input values and then store the result in a temporary variable, sum. */
- sum += *pSrc++;
-
- /* Decrement the loop counter */
- blkCnt--;
- }
- /* 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 variance and then store the result to the destination */
- *pResult = meanOfSquares - squareOfMean;
-
-#else
-
- /* Run the below code for Cortex-M0 */
-
- float32_t sum = 0.0f; /* Temporary result storage */
- float32_t sumOfSquares = 0.0f; /* Sum of squares */
- float32_t squareOfSum; /* Square of Sum */
- float32_t in; /* input value */
- uint32_t blkCnt; /* loop counter */
-
- /* 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 */
- *pResult = ((sumOfSquares - squareOfSum) / (float32_t) (blockSize - 1.0f));
-
-#endif /* #ifndef ARM_MATH_CM0 */
-
-}
-
-/**
- * @} end of variance group
- */
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