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+/* ----------------------------------------------------------------------
+* Copyright (C) 2010-2012 ARM Limited. All rights reserved.
+*
+* $Date: 17. January 2013
+* $Revision: V1.4.0
+*
+* Project: CMSIS DSP Library
+* Title: arm_variance_example_f32.c
+*
+* Description: Example code demonstrating variance calculation of input sequence.
+*
+* Target Processor: Cortex-M4/Cortex-M3
+*
+* Redistribution and use in source and binary forms, with or without
+* modification, are permitted provided that the following conditions
+* are met:
+* - Redistributions of source code must retain the above copyright
+* notice, this list of conditions and the following disclaimer.
+* - Redistributions in binary form must reproduce the above copyright
+* notice, this list of conditions and the following disclaimer in
+* the documentation and/or other materials provided with the
+* distribution.
+* - Neither the name of ARM LIMITED nor the names of its contributors
+* may be used to endorse or promote products derived from this
+* software without specific prior written permission.
+*
+* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+* POSSIBILITY OF SUCH DAMAGE.
+* -------------------------------------------------------------------- */
+
+/**
+ * @ingroup groupExamples
+ */
+
+/**
+ * @defgroup VarianceExample Variance Example
+ *
+ * \par Description:
+ * \par
+ * Demonstrates the use of Basic Math and Support Functions to calculate the variance of an
+ * input sequence with N samples. Uniformly distributed white noise is taken as input.
+ *
+ * \par Algorithm:
+ * \par
+ * The variance of a sequence is the mean of the squared deviation of the sequence from its mean.
+ * \par
+ * This is denoted by the following equation:
+ * <pre> variance = ((x[0] - x') * (x[0] - x') + (x[1] - x') * (x[1] - x') + ... + * (x[n-1] - x') * (x[n-1] - x')) / (N-1)</pre>
+ * where, <code>x[n]</code> is the input sequence, <code>N</code> is the number of input samples, and
+ * <code>x'</code> is the mean value of the input sequence, <code>x[n]</code>.
+ * \par
+ * The mean value <code>x'</code> is defined as:
+ * <pre> x' = (x[0] + x[1] + ... + x[n-1]) / N</pre>
+ *
+ * \par Block Diagram:
+ * \par
+ * \image html Variance.gif
+ *
+ *
+ * \par Variables Description:
+ * \par
+ * \li \c testInput_f32 points to the input data
+ * \li \c wire1, \c wir2, \c wire3 temporary buffers
+ * \li \c blockSize number of samples processed at a time
+ * \li \c refVarianceOut reference variance value
+ *
+ * \par CMSIS DSP Software Library Functions Used:
+ * \par
+ * - arm_dot_prod_f32()
+ * - arm_mult_f32()
+ * - arm_sub_f32()
+ * - arm_fill_f32()
+ * - arm_copy_f32()
+ *
+ * <b> Refer </b>
+ * \link arm_variance_example_f32.c \endlink
+ *
+ */
+
+
+/** \example arm_variance_example_f32.c
+ */
+
+#include <math.h>
+#include "arm_math.h"
+
+/* ----------------------------------------------------------------------
+* Defines each of the tests performed
+* ------------------------------------------------------------------- */
+#define MAX_BLOCKSIZE 32
+#define DELTA (0.000001f)
+
+
+/* ----------------------------------------------------------------------
+* Declare I/O buffers
+* ------------------------------------------------------------------- */
+float32_t wire1[MAX_BLOCKSIZE];
+float32_t wire2[MAX_BLOCKSIZE];
+float32_t wire3[MAX_BLOCKSIZE];
+
+/* ----------------------------------------------------------------------
+* Test input data for Floating point Variance example for 32-blockSize
+* Generated by the MATLAB randn() function
+* ------------------------------------------------------------------- */
+
+float32_t testInput_f32[32] =
+{
+ -0.432564811528221, -1.665584378238097, 0.125332306474831, 0.287676420358549,
+ -1.146471350681464, 1.190915465642999, 1.189164201652103, -0.037633276593318,
+ 0.327292361408654, 0.174639142820925, -0.186708577681439, 0.725790548293303,
+ -0.588316543014189, 2.183185818197101, -0.136395883086596, 0.113931313520810,
+ 1.066768211359189, 0.059281460523605, -0.095648405483669, -0.832349463650022,
+ 0.294410816392640, -1.336181857937804, 0.714324551818952, 1.623562064446271,
+ -0.691775701702287, 0.857996672828263, 1.254001421602532, -1.593729576447477,
+ -1.440964431901020, 0.571147623658178, -0.399885577715363, 0.689997375464345
+
+};
+
+/* ----------------------------------------------------------------------
+* Declare Global variables
+* ------------------------------------------------------------------- */
+uint32_t blockSize = 32;
+float32_t refVarianceOut = 0.903941793931839;
+
+/* ----------------------------------------------------------------------
+* Variance calculation test
+* ------------------------------------------------------------------- */
+
+int32_t main(void)
+{
+ arm_status status;
+ float32_t mean, oneByBlockSize;
+ float32_t variance;
+ float32_t diff;
+
+ status = ARM_MATH_SUCCESS;
+
+#if defined(FILEIO)
+ printf("START\n");
+#endif
+
+
+ /* Calculation of mean value of input */
+
+ /* x' = 1/blockSize * (x(0)* 1 + x(1) * 1 + ... + x(n-1) * 1) */
+
+ /* Fill wire1 buffer with 1.0 value */
+ arm_fill_f32(1.0, wire1, blockSize);
+
+ /* Calculate the dot product of wire1 and wire2 */
+ /* (x(0)* 1 + x(1) * 1 + ...+ x(n-1) * 1) */
+ arm_dot_prod_f32(testInput_f32, wire1, blockSize, &mean);
+
+ /* Calculation of 1/blockSize */
+ oneByBlockSize = 1.0 / (blockSize);
+
+ /* 1/blockSize * (x(0)* 1 + x(1) * 1 + ... + x(n-1) * 1) */
+ arm_mult_f32(&mean, &oneByBlockSize, &mean, 1);
+
+
+ /* Calculation of variance value of input */
+
+ /* (1/blockSize) * (x(0) - x') * (x(0) - x') + (x(1) - x') * (x(1) - x') + ... + (x(n-1) - x') * (x(n-1) - x') */
+
+ /* Fill wire2 with mean value x' */
+ arm_fill_f32(mean, wire2, blockSize);
+
+ /* wire3 contains (x-x') */
+ arm_sub_f32(testInput_f32, wire2, wire3, blockSize);
+
+ /* wire2 contains (x-x') */
+ arm_copy_f32(wire3, wire2, blockSize);
+
+ /* (x(0) - x') * (x(0) - x') + (x(1) - x') * (x(1) - x') + ... + (x(n-1) - x') * (x(n-1) - x') */
+ arm_dot_prod_f32(wire2, wire3, blockSize, &variance);
+
+ /* Calculation of 1/blockSize */
+ oneByBlockSize = 1.0 / (blockSize - 1);
+
+ /* Calculation of variance */
+ arm_mult_f32(&variance, &oneByBlockSize, &variance, 1);
+
+ /* absolute value of difference between ref and test */
+ diff = fabsf(refVarianceOut - variance);
+
+ /* Comparison of variance value with reference */
+
+ if (diff > DELTA)
+ {
+ status = ARM_MATH_TEST_FAILURE;
+ }
+
+
+#if !defined(FILEIO)
+ if ( status != ARM_MATH_SUCCESS)
+ {
+ while (1);
+ }
+
+ while (1); /* main function does not return */
+#else
+ if (status == ARM_MATH_SUCCESS)
+ {
+ printf("SUCCESS\n");
+ }
+ else
+ {
+ printf("FAILURE\n");
+ }
+#endif
+}
+
+ /** \endlink */
+
+