arm_variance_example_f32.c

/* ----------------------------------------------------------------------     
* Copyright (C) 2011 ARM Limited. All rights reserved. 
*     
* $Date:        15. December 2011   
* $Revision:    V2.0.0  
*     
* Project:      Cortex-R4 DSP Library 
* Title:        arm_variance_example_f32.c       
* 
* Description:  Example code demonstrating variance calculation of input sequence.
*     
* Target Processor:          Cortex-R4
*
* Version 2.0.0 2011/12/15
*     Final release. 
* 
* ---------------------------------------------------------------------------- */ 

#include <math.h>    
#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);
    }
}