IDL Reference Guide: Procedures and Functions

MATRIX_POWER

The MATRIX_POWER function computes the product of a matrix with itself. For example, the fifth power of array A is A # A # A # A # A. Negative powers are computed using the matrix inverse of the positive power.

Syntax

Result = MATRIX_POWER(Array, N [, /DOUBLE] [, STATUS=value])

Return Value

The result is a square array containing the value of the matrix raised to the specified power. A power of zero returns the identity matrix.

Arguments

Array

A square, two-dimensional array of any numeric type.

N

An integer representing the power. N may be positive or negative.

Keywords

DOUBLE

Set this keyword to return a double-precision result. Explicitly set this keyword equal to zero to return a single-precision result. The default return type depends upon the precision of Array.

STATUS

Set this keyword equal to a named variable that will contain the status of the matrix inverse for negative powers. Possible values are:

For non-negative powers, STATUS is always set to 0.

Example

Print an array to the one millionth power:

array = [ [0.401d, 0.600d], $  
          [0.525d, 0.475d] ]  
PRINT, MATRIX_POWER(array, 1e6)  

IDL prints:

  2.4487434e+202  2.7960773e+202  
  2.4465677e+202  2.7935929e+202