arm_variance_example_f32.c
1 /* ---------------------------------------------------------------------- 2 * Copyright (C) 2010-2012 ARM Limited. All rights reserved. 3 * 4 * $Date: 17. January 2013 5 * $Revision: V1.4.0 6 * 7 * Project: CMSIS DSP Library 8 * Title: arm_variance_example_f32.c 9 * 10 * Description: Example code demonstrating variance calculation of input sequence. 11 * 12 * Target Processor: Cortex-M4/Cortex-M3 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * - Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * - Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in 21 * the documentation and/or other materials provided with the 22 * distribution. 23 * - Neither the name of ARM LIMITED nor the names of its contributors 24 * may be used to endorse or promote products derived from this 25 * software without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 38 * POSSIBILITY OF SUCH DAMAGE. 39 * -------------------------------------------------------------------- */ 40 41 /** 42 * @ingroup groupExamples 43 */ 44 45 /** 46 * @defgroup VarianceExample Variance Example 47 * 48 * \par Description: 49 * \par 50 * Demonstrates the use of Basic Math and Support Functions to calculate the variance of an 51 * input sequence with N samples. Uniformly distributed white noise is taken as input. 52 * 53 * \par Algorithm: 54 * \par 55 * The variance of a sequence is the mean of the squared deviation of the sequence from its mean. 56 * \par 57 * This is denoted by the following equation: 58 * <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> 59 * where, <code>x[n]</code> is the input sequence, <code>N</code> is the number of input samples, and 60 * <code>x'</code> is the mean value of the input sequence, <code>x[n]</code>. 61 * \par 62 * The mean value <code>x'</code> is defined as: 63 * <pre> x' = (x[0] + x[1] + ... + x[n-1]) / N</pre> 64 * 65 * \par Block Diagram: 66 * \par 67 * \image html Variance.gif 68 * 69 * 70 * \par Variables Description: 71 * \par 72 * \li \c testInput_f32 points to the input data 73 * \li \c wire1, \c wir2, \c wire3 temporary buffers 74 * \li \c blockSize number of samples processed at a time 75 * \li \c refVarianceOut reference variance value 76 * 77 * \par CMSIS DSP Software Library Functions Used: 78 * \par 79 * - arm_dot_prod_f32() 80 * - arm_mult_f32() 81 * - arm_sub_f32() 82 * - arm_fill_f32() 83 * - arm_copy_f32() 84 * 85 * <b> Refer </b> 86 * \link arm_variance_example_f32.c \endlink 87 * 88 */ 89 90 91 /** \example arm_variance_example_f32.c 92 */ 93 94 #include <math.h> 95 #include "arm_math.h" 96 97 #if defined(SEMIHOSTING) 98 #include <stdio.h> 99 #endif 100 101 /* ---------------------------------------------------------------------- 102 * Defines each of the tests performed 103 * ------------------------------------------------------------------- */ 104 #define MAX_BLOCKSIZE 32 105 #define DELTA (0.000001f) 106 107 108 /* ---------------------------------------------------------------------- 109 * Declare I/O buffers 110 * ------------------------------------------------------------------- */ 111 float32_t wire1[MAX_BLOCKSIZE]; 112 float32_t wire2[MAX_BLOCKSIZE]; 113 float32_t wire3[MAX_BLOCKSIZE]; 114 115 /* ---------------------------------------------------------------------- 116 * Test input data for Floating point Variance example for 32-blockSize 117 * Generated by the MATLAB randn() function 118 * ------------------------------------------------------------------- */ 119 120 float32_t testInput_f32[32] = 121 { 122 -0.432564811528221, -1.665584378238097, 0.125332306474831, 0.287676420358549, 123 -1.146471350681464, 1.190915465642999, 1.189164201652103, -0.037633276593318, 124 0.327292361408654, 0.174639142820925, -0.186708577681439, 0.725790548293303, 125 -0.588316543014189, 2.183185818197101, -0.136395883086596, 0.113931313520810, 126 1.066768211359189, 0.059281460523605, -0.095648405483669, -0.832349463650022, 127 0.294410816392640, -1.336181857937804, 0.714324551818952, 1.623562064446271, 128 -0.691775701702287, 0.857996672828263, 1.254001421602532, -1.593729576447477, 129 -1.440964431901020, 0.571147623658178, -0.399885577715363, 0.689997375464345 130 131 }; 132 133 /* ---------------------------------------------------------------------- 134 * Declare Global variables 135 * ------------------------------------------------------------------- */ 136 uint32_t blockSize = 32; 137 float32_t refVarianceOut = 0.903941793931839; 138 139 /* ---------------------------------------------------------------------- 140 * Variance calculation test 141 * ------------------------------------------------------------------- */ 142 143 int32_t main(void) 144 { 145 arm_status status; 146 float32_t mean, oneByBlockSize; 147 float32_t variance; 148 float32_t diff; 149 150 status = ARM_MATH_SUCCESS; 151 152 #if defined(SEMIHOSTING) 153 printf("START\n"); 154 #endif 155 156 157 /* Calculation of mean value of input */ 158 159 /* x' = 1/blockSize * (x(0)* 1 + x(1) * 1 + ... + x(n-1) * 1) */ 160 161 /* Fill wire1 buffer with 1.0 value */ 162 arm_fill_f32(1.0, wire1, blockSize); 163 164 /* Calculate the dot product of wire1 and wire2 */ 165 /* (x(0)* 1 + x(1) * 1 + ...+ x(n-1) * 1) */ 166 arm_dot_prod_f32(testInput_f32, wire1, blockSize, &mean); 167 168 /* Calculation of 1/blockSize */ 169 oneByBlockSize = 1.0 / (blockSize); 170 171 /* 1/blockSize * (x(0)* 1 + x(1) * 1 + ... + x(n-1) * 1) */ 172 arm_mult_f32(&mean, &oneByBlockSize, &mean, 1); 173 174 175 /* Calculation of variance value of input */ 176 177 /* (1/blockSize) * (x(0) - x') * (x(0) - x') + (x(1) - x') * (x(1) - x') + ... + (x(n-1) - x') * (x(n-1) - x') */ 178 179 /* Fill wire2 with mean value x' */ 180 arm_fill_f32(mean, wire2, blockSize); 181 182 /* wire3 contains (x-x') */ 183 arm_sub_f32(testInput_f32, wire2, wire3, blockSize); 184 185 /* wire2 contains (x-x') */ 186 arm_copy_f32(wire3, wire2, blockSize); 187 188 /* (x(0) - x') * (x(0) - x') + (x(1) - x') * (x(1) - x') + ... + (x(n-1) - x') * (x(n-1) - x') */ 189 arm_dot_prod_f32(wire2, wire3, blockSize, &variance); 190 191 /* Calculation of 1/blockSize */ 192 oneByBlockSize = 1.0 / (blockSize - 1); 193 194 /* Calculation of variance */ 195 arm_mult_f32(&variance, &oneByBlockSize, &variance, 1); 196 197 /* absolute value of difference between ref and test */ 198 diff = fabsf(refVarianceOut - variance); 199 200 /* Comparison of variance value with reference */ 201 status = (diff > DELTA) ? ARM_MATH_TEST_FAILURE : ARM_MATH_SUCCESS; 202 203 if (status != ARM_MATH_SUCCESS) 204 { 205 #if defined (SEMIHOSTING) 206 printf("FAILURE\n"); 207 #else 208 while (1); /* main function does not return */ 209 #endif 210 } 211 else 212 { 213 #if defined (SEMIHOSTING) 214 printf("SUCCESS\n"); 215 #else 216 while (1); /* main function does not return */ 217 #endif 218 } 219 220 } 221 222 /** \endlink */ 223 224