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;
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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
main(void)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
225
