Variance Example

Table of Contents

• Introduction
• Supported Combinations
• Using SDK with SysConfig
• Steps to Run the Example
• Sample Output

Introduction

This example demonstrates the use of Basic Math and Support Functions to calculate the variance of an input sequence with N samples. Uniformly distributed white noise is taken as input. As per the algorithm, variance of a sequence is the mean of the squared deviation of the sequence from its mean.This is denoted by the following equation:

 variance = ((x[0] - x') * (x[0] - x') + (x[1] - x') * (x[1] - x') + ... + * (x[n-1] - x') * (x[n-1] - x')) / (N-1)

where, x[n] is the input sequence, N is the number of input samples, and x' is the mean value of the input sequence, The mean value x' is defined as:

 x' = (x[0] + x[1] + ... + x[n-1]) / N

. CMSIS DSP Software Library Functions which are being used in this example are as follows:

• arm_dot_prod_f32()
• arm_mult_f32()
• arm_sub_f32()
• arm_fill_f32()
• arm_copy_f32()

Supported Combinations

Parameter	Value
CPU + OS	m4fss0-0 freertos
	m4fss0-0 nortos
Toolchain	ti-arm-clang
Boards	xWRL6432-evm
Example folder	examples/cmsis-dsp/arm_variance_example/

Using SDK with SysConfig

A GUI tool SysConfig is used to configure different modules and peripherals of the example. Using this tool, users can select and customize different modules and peripherals. The SysConfig tool will generate the code for initializing and configuring these modules. This configuration is saved to a file called example.syscfg for every example. To know more about how to use SDK with SysConfig, Visit this page

Using SDK with SysConfig

Steps to Run the Example

• When using CCS projects to build, import the CCS project for the required combination and build it using the CCS project menu (see Using SDK with CCS Projects).
• When using makefiles to build, note the required combination and build using make command (see Using SDK with Makefiles)
• Launch a CCS debug session and run the executable, see CCS Launch, Load and Run

Sample Output

Shown below is a sample output when the application is run,

Variance Example Started
Variance Example Passed