# Knowledge Base

 Navigation: Scripting Language > Functions cov

Calculates the covariance matrix. The input can be one matrix, which contains the observations of a set of random variables, or two matrices, each one representing a vector of observations.

 Supported Product: FDTD, MODE, DEVICE, INTERCONNECT

 Syntax Description cov(A); cov(A, B); Calculate the covariance matrix.   C = cov(A) returns the covariance. A is a matrix where columns represent random variables and rows represent observations; C is the covariance matrix with the corresponding column variances along the diagonal.   C = cov(A, B) returns the covariance between two random variables A and B. If A and B are vectors of observations with equal length, cov(A, B) is the 2-by-2 covariance matrix; if A and B are matrices of observations, cov(A, B) treats A and B as vectors and is equivalent to cov(A(1:lenght(A)), B(1:length(B))). A and B must have equal size.

Example

The following examples illustrate how to find the covariance matrix.

A = [1,2;3,4];

B = [1.1,2.7; 2.5, 4.3];

?cov(A,B);

?cov(A(1:length(A)),B(1:length(B)));

result:

1.25  1.175

1.175  1.2875

result:

1.25  1.175

1.175  1.2875