variance

float  variance(float variable, float &mean, int &sample_size)

This function will compute the mean and variance from nearby samples. Similar to the way that VEX is able to compute derivatives, this function is able to inspect the variable for a nearby area and compute the mean and variance of the variable.

The function returns the variance (σ2). The mean value will also be returned along with the sample_size indicating how many nearby samples were considered.