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 * @addtogroup groupExamples
43 * @{
44 *
45 * @defgroup VarianceExample Variance Example
46 *
47 * \par Description:
48 * \par
49 * Demonstrates the use of Basic Math and Support Functions to calculate the variance of an
50 * input sequence with N samples. Uniformly distributed white noise is taken as input.
51 *
52 * \par Algorithm:
53 * \par
54 * The variance of a sequence is the mean of the squared deviation of the sequence from its mean.
55 * \par
56 * This is denoted by the following equation:
57 * <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>
58 * where, <code>x[n]</code> is the input sequence, <code>N</code> is the number of input samples, and
59 * <code>x'</code> is the mean value of the input sequence, <code>x[n]</code>.
60 * \par
61 * The mean value <code>x'</code> is defined as:
62 * <pre> x' = (x[0] + x[1] + ... + x[n-1]) / N</pre>
63 *
64 * \par Block Diagram:
65 * \par
66 * \image html Variance.gif
67 *
68 *
69 * \par Variables Description:
70 * \par
71 * \li \c testInput_f32 points to the input data
72 * \li \c wire1, \c wir2, \c wire3 temporary buffers
73 * \li \c blockSize number of samples processed at a time
74 * \li \c refVarianceOut reference variance value
75 *
76 * \par CMSIS DSP Software Library Functions Used:
77 * \par
78 * - arm_dot_prod_f32()
79 * - arm_mult_f32()
80 * - arm_sub_f32()
81 * - arm_fill_f32()
82 * - arm_copy_f32()
83 *
84 * <b> Refer </b>
85 * \link arm_variance_example_f32.c \endlink
86 *
87 * \example arm_variance_example_f32.c
88 *
89 * @} */
90
91 #include <math.h>
92 #include "arm_math.h"
93
94 #if defined(SEMIHOSTING)
95 #include <stdio.h>
96 #endif
97
98 /* ----------------------------------------------------------------------
99 * Defines each of the tests performed
100 * ------------------------------------------------------------------- */
101 #define MAX_BLOCKSIZE 32
102 #define DELTA (0.000001f)
103
104
105 /* ----------------------------------------------------------------------
106 * Declare I/O buffers
107 * ------------------------------------------------------------------- */
108 float32_t wire1[MAX_BLOCKSIZE];
109 float32_t wire2[MAX_BLOCKSIZE];
110 float32_t wire3[MAX_BLOCKSIZE];
111
112 /* ----------------------------------------------------------------------
113 * Test input data for Floating point Variance example for 32-blockSize
114 * Generated by the MATLAB randn() function
115 * ------------------------------------------------------------------- */
116
117 float32_t testInput_f32[32] =
118 {
119 -0.432564811528221, -1.665584378238097, 0.125332306474831, 0.287676420358549,
120 -1.146471350681464, 1.190915465642999, 1.189164201652103, -0.037633276593318,
121 0.327292361408654, 0.174639142820925, -0.186708577681439, 0.725790548293303,
122 -0.588316543014189, 2.183185818197101, -0.136395883086596, 0.113931313520810,
123 1.066768211359189, 0.059281460523605, -0.095648405483669, -0.832349463650022,
124 0.294410816392640, -1.336181857937804, 0.714324551818952, 1.623562064446271,
125 -0.691775701702287, 0.857996672828263, 1.254001421602532, -1.593729576447477,
126 -1.440964431901020, 0.571147623658178, -0.399885577715363, 0.689997375464345
127
128 };
129
130 /* ----------------------------------------------------------------------
131 * Declare Global variables
132 * ------------------------------------------------------------------- */
133 uint32_t blockSize = 32;
134 float32_t refVarianceOut = 0.903941793931839;
135
136 /* ----------------------------------------------------------------------
137 * Variance calculation test
138 * ------------------------------------------------------------------- */
139
main(void)140 int32_t main(void)
141 {
142 arm_status status;
143 float32_t mean, oneByBlockSize;
144 float32_t variance;
145 float32_t diff;
146
147 status = ARM_MATH_SUCCESS;
148
149 #if defined(SEMIHOSTING)
150 printf("START\n");
151 #endif
152
153
154 /* Calculation of mean value of input */
155
156 /* x' = 1/blockSize * (x(0)* 1 + x(1) * 1 + ... + x(n-1) * 1) */
157
158 /* Fill wire1 buffer with 1.0 value */
159 arm_fill_f32(1.0, wire1, blockSize);
160
161 /* Calculate the dot product of wire1 and wire2 */
162 /* (x(0)* 1 + x(1) * 1 + ...+ x(n-1) * 1) */
163 arm_dot_prod_f32(testInput_f32, wire1, blockSize, &mean);
164
165 /* Calculation of 1/blockSize */
166 oneByBlockSize = 1.0 / (blockSize);
167
168 /* 1/blockSize * (x(0)* 1 + x(1) * 1 + ... + x(n-1) * 1) */
169 arm_mult_f32(&mean, &oneByBlockSize, &mean, 1);
170
171
172 /* Calculation of variance value of input */
173
174 /* (1/blockSize) * (x(0) - x') * (x(0) - x') + (x(1) - x') * (x(1) - x') + ... + (x(n-1) - x') * (x(n-1) - x') */
175
176 /* Fill wire2 with mean value x' */
177 arm_fill_f32(mean, wire2, blockSize);
178
179 /* wire3 contains (x-x') */
180 arm_sub_f32(testInput_f32, wire2, wire3, blockSize);
181
182 /* wire2 contains (x-x') */
183 arm_copy_f32(wire3, wire2, blockSize);
184
185 /* (x(0) - x') * (x(0) - x') + (x(1) - x') * (x(1) - x') + ... + (x(n-1) - x') * (x(n-1) - x') */
186 arm_dot_prod_f32(wire2, wire3, blockSize, &variance);
187
188 /* Calculation of 1/blockSize */
189 oneByBlockSize = 1.0 / (blockSize - 1);
190
191 /* Calculation of variance */
192 arm_mult_f32(&variance, &oneByBlockSize, &variance, 1);
193
194 /* absolute value of difference between ref and test */
195 diff = fabsf(refVarianceOut - variance);
196
197 /* Comparison of variance value with reference */
198 status = (diff > DELTA) ? ARM_MATH_TEST_FAILURE : ARM_MATH_SUCCESS;
199
200 if (status != ARM_MATH_SUCCESS)
201 {
202 #if defined (SEMIHOSTING)
203 printf("FAILURE\n");
204 #else
205 while (1); /* main function does not return */
206 #endif
207 }
208 else
209 {
210 #if defined (SEMIHOSTING)
211 printf("SUCCESS\n");
212 #else
213 while (1); /* main function does not return */
214 #endif
215 }
216
217 }
218
219 /** \endlink */
220
221
222
