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Variance

Variance (inWave [ , x1, x2 ] )​

Returns the variance of the real-valued inWave . The function ignores NaN and INF values in inWave .

Parameters​

inWave is expected to be a real-valued numeric wave. If inWave is a complex or text wave, Variance returns NaN.

x1 and x2 specify a range in inWave over which the variance is to be calculated. They are used only to locate the points nearest to x=x1 and x=x2 . The variance is then calculated over that range of points. The order of x1 and x2 is immaterial.

If omitted, x1 and x2 default to -INF and +INF respectively and the variance is calculated for the entire wave.

Details​

The variance is defined by

var⁡=∑i=1n(xi−xˉ)2n−1\displaystyle \operatorname{var}=\frac{\sum_{i=1}^{n}\left(x_{i}-\bar{x}\right)^{2}}{n-1}

where

xˉ=∑i=1nXin.\displaystyle \bar{x}=\frac{\sum_{i=1}^{n} X_{i}}{n} .

Examples​

Make/O/N=5 test = p
SetScale/P x, 0, .1, test

// Print variance of entire wave
Print Variance(test)

// Print variance from x=0 to x=.2
Print Variance(test, 0, .2)

// Print variance for points 1 through 3
Variable x1=pnt2x(test, 1)
Variable x2=pnt2x(test, 3)
Print Variance(test, x1, x2)

See Also​

mean, median, WaveStats, APMath