/* ---------------------------------------------------------------------- * 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: * 
 variance = ((x[0] - x') * (x[0] - x') + (x[1] - x') * (x[1] - x') + ... + * (x[n-1] - x') * (x[n-1] - x')) / (N-1)
* where, x[n] is the input sequence, N is the number of input samples, and * x' is the mean value of the input sequence, x[n]. * \par * The mean value x' is defined as: * 
 x' = (x[0] + x[1] + ... + x[n-1]) / N
* * \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() * * Refer * \link arm_variance_example_f32.c \endlink * */ /** \example arm_variance_example_f32.c */ #include #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; /* 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( status != ARM_MATH_SUCCESS) { while(1); } while(1); /* main function does not return */ } /** \endlink */