# Difference between revisions of "ApCoCoA-1:Num.EigenValuesAndVectors"

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## Revision as of 16:45, 23 April 2009

## Num.EigenValuesAndVectors

Computes the eigenvalues and eigenvectors of a matrix

### Syntax

Num.EigenValuesAndVectors(A:Matrix):[B:Matrix, C:Matrix, D:Matrix]

### Description

*Please note:* The function(s) explained on this page is/are using the *ApCoCoAServer*. You will have to start the ApCoCoAServer in order to use it/them.

This function returns a list of three matrices, containing numerical approximation to the eigenvalues of A and (right hand) eigenvectors.

@param

*A*A square matrix with rational entries.@return The output [B:Matrix, C:Matrix, D:Matrix] contains a matrix B, where each column contains one of A's eigenvalues. The first row contains the eigenvalue's real part, the second row the imaginary. The matrices C and D both have the same dimensions as A. Column j of matrix C contains the real part of the eigenvector corresponding to eigenvalue j and column j of matrix D contains the imaginary part of the eigenvector correspsonding to eigenvalue j.

To compute only the left hand eigenvectors apply this method to the transposed matrix of A.

#### Example

A:=Mat([[1,2,7,18],[2,4,9,12],[23,8,9,10],[7,5,3,2]]); Dec(Num.EigenValuesAndVectors(A),3); -- CoCoAServer: computing Cpu Time = 0.016 ------------------------------- [Mat([ ["28.970", "-13.677", "0.353", "0.353"], ["0", "0", "3.051", "-3.051"] ]), Mat([ ["0.394", "-0.581", "0.260", "0.260"], ["0.435", "-0.442", "-0.547", "-0.547"], ["0.763", "0.621", "0", "0"], ["0.268", "0.281", "0.046", "0.046"] ]), Mat([ ["0", "0", "-0.031", "0.031"], ["0", "0", "-0.301", "0.301"], ["0", "0", "0.680", "-0.680"], ["0", "0", "-0.274", "0.274"] ])] --------------------------------------------------------------

### See also