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Diffstat (limited to 'Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_var_f64.c')
-rw-r--r-- | Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_var_f64.c | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_var_f64.c b/Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_var_f64.c new file mode 100644 index 0000000..6fd106a --- /dev/null +++ b/Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_var_f64.c @@ -0,0 +1,100 @@ +/* ---------------------------------------------------------------------- + * Project: CMSIS DSP Library + * Title: arm_var_f64.c + * Description: Variance of the elements of a floating-point vector + * + * $Date: 13 September 2021 + * $Revision: V1.10.0 + * + * 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 + */ + +/** + @addtogroup variance + @{ + */ + +/** + @brief Variance 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 variance value returned here + @return none + */ +void arm_var_f64( + const float64_t * pSrc, + uint32_t blockSize, + float64_t * pResult) +{ + uint32_t blkCnt; /* Loop counter */ + float64_t sum = 0.; /* Temporary result storage */ + float64_t fSum = 0.; + float64_t fMean, fValue; + const float64_t * pInput = pSrc; + + if (blockSize <= 1U) + { + *pResult = 0; + return; + } + + /* Initialize blkCnt with number of samples */ + blkCnt = blockSize; + + while (blkCnt > 0U) + { + /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */ + + sum += *pInput++; + + /* Decrement loop counter */ + blkCnt--; + } + + /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) / blockSize */ + fMean = sum / (float64_t) blockSize; + + pInput = pSrc; + + /* Initialize blkCnt with number of samples */ + blkCnt = blockSize; + + while (blkCnt > 0U) + { + fValue = *pInput++ - fMean; + fSum += fValue * fValue; + + /* Decrement loop counter */ + blkCnt--; + } + + /* Variance */ + *pResult = fSum / (float64_t)(blockSize - 1.); +} + +/** + @} end of variance group + */ |