var

Return variance values in DataMatrix object

Syntax

V = var(DMObj)
V = var(DMObj, Flag)
V = var(DMObj, Wgt)
V = var(..., Dim)
V = var(..., Dim, IgnoreNaN)

Input Arguments

DMObj

DataMatrix object, such as created by DataMatrix (object constructor).

Flag

Scalar specifying how to normalize the data. Choices are:

  • 0 — Default. Normalizes using a sample size of N – 1, unless N = 1, in which case, normalizes using a sample size of 1.

  • 1 — Normalizes using a sample size of N.

N = the number of elements in each column or row, as specified by Dim. For more information on the normalization equations, see the function std.

WgtWeight vector equal in length to the dimension over which var operates (specified by Dim. It is used to compute the variance.
Dim

Scalar specifying the dimension of DMObj to calculate the variances. Choices are:

  • 1 — Default. Returns variance values for elements in each column.

  • 2 — Returns variance values for elements in each row.

IgnoreNaN

Specifies if NaNs should be ignored. Choices are true (default) or false.

Output Arguments

V

An unbiased estimator of the variance within the columns or rows of a DataMatrix object. It can be either of the following:

  • Row vector containing the variance values from elements in each column in DMObj (when Dim = 1)

  • Column vector containing the variance values from elements in each row in DMObj (when Dim = 2)

Description

V = var(DMObj) returns the variance values of the elements in the columns of a DataMatrix object, treating NaNs as missing values. The data is normalized using a sample size of N – 1, where N = the number of elements in each column. V is a row vector containing the variance values for elements in each column in DMObj. The variance is the square of the standard deviation.

V = var(DMObj, Flag) specifies how to normalize the data. If Flag = 0, normalizes using a sample size of N – 1. If Flag = 1, normalizes using a sample size of N. N = the number of elements in each column or row, as specified by Dim. For more information on the normalization equations, see the function std. Default Flag = 0.

V = var(DMObj, Wgt) computes the variance using Wgt, a weight vector whose length must equal the length of the dimension over which var operates (specified by Dim). All elements in Wgt must be nonnegative. The var function normalizes Wgt to sum of 1.

V = var(..., Dim) returns the variance values of the elements in the columns or rows of a DataMatrix object, as specified by Dim. If Dim = 1, returns V, a row vector containing the variance values for elements in each column in DMObj. If Dim = 2, returns V, a column vector containing the variance values for elements in each row in DMObj. Default Dim = 1.

V = var(..., Dim, IgnoreNaN) specifies if NaNs should be ignored. IgnoreNaN can be true (default) or false.

Version History

Introduced in R2008b

See Also

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