text: /*
   * Copyright (C) 2015 Eistec AB
   *
   * This file is subject to the terms and conditions of the GNU Lesser
   * General Public License v2.1. See the file LICENSE in the top level
   * directory for more details.
   */
  
  /**
   * @ingroup     examples
   * @{
   *
   * @file
   * @brief       ARM DSP library test application
   *
   * @author      Joakim Nohlgård <joakim.nohlgard@eistec.se>
   *
   * @}
   */
  
  #include <stdio.h>
  #include <stdint.h>
  #include <math.h>
  #include "arm_math.h"
  
  #define MAX_BLOCKSIZE   32
  #define DELTA           (0.0000001f)
  /* ----------------------------------------------------------------------
  * 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
  * ------------------------------------------------------------------- */
  int main(void)
  {
      arm_status status;
      float32_t mean;
      float32_t oneByBlockSize = 1.0 / (blockSize);
      float32_t variance;
      float32_t diff;
      status = ARM_MATH_SUCCESS;
      puts("ARM DSP lib test");
      puts("Note: This test is using 32 bit IEEE 754 floating point numbers,"
           "(24 bit mantissa, 7 bit exponent)");
      puts("Expect roughly 7 decimals precision on the result.");
      /* 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);
      /* 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 = variance - refVarianceOut;
      /* Split into fractional and integral parts, since printing floats may not be supported on all platforms */
      float int_part;
      float frac_part = fabsf(modff(variance, &int_part));
      printf("      dsp: %3d.%09d\n", (int) int_part, (int) (frac_part * 1.0e9f + 0.5f));
      puts(  "reference:   0.903941793931839");
      frac_part = fabsf(modff(diff, &int_part));
      printf("     diff: %3d.%09d\n", (int) int_part, (int) (frac_part * 1.0e9f + 0.5f));
      /* Comparison of variance value with reference */
      if(fabsf(diff) > DELTA) {
          status = ARM_MATH_TEST_FAILURE;
      }
      if(status != ARM_MATH_SUCCESS) {
          puts("Test failed");
          while(1)
              ;
      }
      puts("Test done");
      while(1)
          ; /* main function does not return */
  }
  