1 /* ----------------------------------------------------------------------
2 * Copyright (C) 2010 ARM Limited. All rights reserved.
3 *
4 * $Date: 29. November 2010
5 * $Revision: V1.0.3
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 *
15 * Version 1.0.3 2010/11/29
16 * Re-organized the CMSIS folders and updated documentation.
17 *
18 * Version 1.0.1 2010/10/05 KK
19 * Production release and review comments incorporated.
20 *
21 * Version 1.0.0 2010/09/20 KK
22 * Production release and review comments incorporated.
23 * ------------------------------------------------------------------- */
24
25 /**
26 * @ingroup groupExamples
27 */
28
29 /**
30 * @defgroup VarianceExample Variance Example
31 *
32 * \par Description:
33 * \par
34 * Demonstrates the use of Basic Math and Support Functions to calculate the variance of an
35 * input sequence with N samples. Uniformly distributed white noise is taken as input.
36 *
37 * \par Algorithm:
38 * \par
39 * The variance of a sequence is the mean of the squared deviation of the sequence from its mean.
40 * \par
41 * This is denoted by the following equation:
42 * <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>
43 * where, <code>x[n]</code> is the input sequence, <code>N</code> is the number of input samples, and
44 * <code>x'</code> is the mean value of the input sequence, <code>x[n]</code>.
45 * \par
46 * The mean value <code>x'</code> is defined as:
47 * <pre> x' = (x[0] + x[1] + ... + x[n-1]) / N</pre>
48 *
49 * \par Block Diagram:
50 * \par
51 * \image html Variance.gif
52 *
53 *
54 * \par Variables Description:
55 * \par
56 * \li \c testInput_f32 points to the input data
57 * \li \c wire1, \c wir2, \c wire3 temporary buffers
58 * \li \c blockSize number of samples processed at a time
59 * \li \c refVarianceOut reference variance value
60 *
61 * \par CMSIS DSP Software Library Functions Used:
62 * \par
63 * - arm_dot_prod_f32()
64 * - arm_mult_f32()
65 * - arm_sub_f32()
66 * - arm_fill_f32()
67 * - arm_copy_f32()
68 *
69 * <b> Refer </b>
70 * \link arm_variance_example_f32.c \endlink
71 *
72 */
73
74
75 /** \example arm_variance_example_f32.c
76 */
77 #include <math.h>
78 #include "arm_math.h"
79
80 /* ----------------------------------------------------------------------
81 * Defines each of the tests performed
82 * ------------------------------------------------------------------- */
83 #define MAX_BLOCKSIZE 32
84 #define DELTA (0.000001f)
85
86
87 /* ----------------------------------------------------------------------
88 * Declare I/O buffers
89 * ------------------------------------------------------------------- */
90 float32_t wire1[MAX_BLOCKSIZE];
91 float32_t wire2[MAX_BLOCKSIZE];
92 float32_t wire3[MAX_BLOCKSIZE];
93
94 /* ----------------------------------------------------------------------
95 * Test input data for Floating point Variance example for 32-blockSize
96 * Generated by the MATLAB randn() function
97 * ------------------------------------------------------------------- */
98
99 float32_t testInput_f32[32] =
100 {
101 -0.432564811528221, -1.665584378238097, 0.125332306474831, 0.287676420358549,
102 -1.146471350681464, 1.190915465642999, 1.189164201652103, -0.037633276593318,
103 0.327292361408654, 0.174639142820925, -0.186708577681439, 0.725790548293303,
104 -0.588316543014189, 2.183185818197101, -0.136395883086596, 0.113931313520810,
105 1.066768211359189, 0.059281460523605, -0.095648405483669, -0.832349463650022,
106 0.294410816392640, -1.336181857937804, 0.714324551818952, 1.623562064446271,
107 -0.691775701702287, 0.857996672828263, 1.254001421602532, -1.593729576447477,
108 -1.440964431901020, 0.571147623658178, -0.399885577715363, 0.689997375464345
109
110 };
111
112 /* ----------------------------------------------------------------------
113 * Declare Global variables
114 * ------------------------------------------------------------------- */
115 uint32_t blockSize = 32;
116 float32_t refVarianceOut = 0.903941793931839;
117
118 /* ----------------------------------------------------------------------
119 * Variance calculation test
120 * ------------------------------------------------------------------- */
121
main(void)122 int32_t main(void)
123 {
124 arm_status status;
125 float32_t mean, oneByBlockSize;
126 float32_t variance;
127 float32_t diff;
128
129 status = ARM_MATH_SUCCESS;
130
131 /* Calculation of mean value of input */
132
133 /* x' = 1/blockSize * (x(0)* 1 + x(1) * 1 + ... + x(n-1) * 1) */
134
135 /* Fill wire1 buffer with 1.0 value */
136 arm_fill_f32(1.0, wire1, blockSize);
137
138 /* Calculate the dot product of wire1 and wire2 */
139 /* (x(0)* 1 + x(1) * 1 + ...+ x(n-1) * 1) */
140 arm_dot_prod_f32(testInput_f32, wire1, blockSize, &mean);
141
142 /* Calculation of 1/blockSize */
143 oneByBlockSize = 1.0 / (blockSize);
144
145 /* 1/blockSize * (x(0)* 1 + x(1) * 1 + ... + x(n-1) * 1) */
146 arm_mult_f32(&mean, &oneByBlockSize, &mean, 1);
147
148
149 /* Calculation of variance value of input */
150
151 /* (1/blockSize) * (x(0) - x') * (x(0) - x') + (x(1) - x') * (x(1) - x') + ... + (x(n-1) - x') * (x(n-1) - x') */
152
153 /* Fill wire2 with mean value x' */
154 arm_fill_f32(mean, wire2, blockSize);
155
156 /* wire3 contains (x-x') */
157 arm_sub_f32(testInput_f32, wire2, wire3, blockSize);
158
159 /* wire2 contains (x-x') */
160 arm_copy_f32(wire3, wire2, blockSize);
161
162 /* (x(0) - x') * (x(0) - x') + (x(1) - x') * (x(1) - x') + ... + (x(n-1) - x') * (x(n-1) - x') */
163 arm_dot_prod_f32(wire2, wire3, blockSize, &variance);
164
165 /* Calculation of 1/blockSize */
166 oneByBlockSize = 1.0 / (blockSize - 1);
167
168 /* Calculation of variance */
169 arm_mult_f32(&variance, &oneByBlockSize, &variance, 1);
170
171 /* absolute value of difference between ref and test */
172 diff = fabsf(refVarianceOut - variance);
173
174 /* Comparison of variance value with reference */
175 if(diff > DELTA)
176 {
177 status = ARM_MATH_TEST_FAILURE;
178 }
179
180 if( status != ARM_MATH_SUCCESS)
181 {
182 while(1);
183 }
184
185 while(1); /* main function does not return */
186 }
187
188 /** \endlink */
189
190