m^n ( m n -- n )

Vocabulary

math.matrices.extras

Inputs

m	a matrix
n	an object

Outputs

n

an object

Word description

Compute the nth power of the input matrix. If n is -1, the inverse of the matrix is calculated (but see multiplicative-inverse for pitfalls).

Errors

negative-power-matrix if n is a negative number other than -1.

undefined-inverse if n is -1 and the multiplicative-inverse of m is undefined.

Notes

•	This word is the swapped variant of n^m.
•	This word is intended for use with "flat" (2-dimensional) matrices.
•	This word assumes that elements of the input matrix are compatible with the following words: max ( obj1 obj2 -- obj ) abs ( x -- y ) / ( x y -- z )

Examples

USING: math.matrices.extras prettyprint ; { { 1 2 } { 3 4 } } 2 m^n .
{ { 7 10 } { 15 22 } }

Definition

USING: combinators kernel math math.matrices.extras.private ;

IN: math.matrices.extras

: m^n ( m n -- n )
    {
        { [ dup -1 = ] [ drop recip ] }
        { [ dup 0 >= ] [ (m^n) ] }
        [ negative-power-matrix ]
    } cond ;