From 5b81bc8ccbd342b8566d88fc9f17a73aec03b5b6 Mon Sep 17 00:00:00 2001
From: Clyne Sullivan <clyne@bitgloo.com>
Date: Wed, 29 Jan 2025 21:34:25 -0500
Subject: initial commit
---
.../DSP/Source/StatisticsFunctions/arm_std_f32.c | 83 ++++++++++++++++++++++
1 file changed, 83 insertions(+)
create mode 100644 Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_std_f32.c
(limited to 'Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_std_f32.c')
diff --git a/Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_std_f32.c b/Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_std_f32.c
new file mode 100644
index 0000000..682443d
--- /dev/null
+++ b/Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_std_f32.c
@@ -0,0 +1,83 @@
+/* ----------------------------------------------------------------------
+ * 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
+ */
--
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