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 Variance Example CMSIS-DSP: Variance Example
CMSIS-DSP  Version 1.4.7
CMSIS DSP Software Library
Variance Example
Description:
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.
Algorithm:
The 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, x[n].
The mean value x' is defined as:
x' = (x[0] + x[1] + ... + x[n-1]) / N
Block Diagram:
Variables Description:
• testInput_f32 points to the input data
• wire1, wir2, wire3 temporary buffers
• blockSize number of samples processed at a time
• refVarianceOut reference variance value
CMSIS DSP Software Library Functions Used:

Refer arm_variance_example_f32.c