IsIdempotent

Tests if a matrix is idempotent.

Syntax

• IsIdempotent(A[, ε])

  • A is a matrix

  • ε is a positive number

Description

IsIdempotent(A, ε) returns true iff A is idempotent, that is, iff A^2 = A, using ε as the epsilon for floating-point comparisons.

Examples

A ≔ [IdentityMatrix(3) + ReflectionMatrix(❨3, 1, −2❩)] / 2

⎛ 0.357142857143  −0.214285714286   0.428571428571⎞
⎜−0.214285714286   0.928571428571   0.142857142857⎟
⎝ 0.428571428571   0.142857142857   0.714285714286⎠

IsIdempotent(A)

true

See also

• IsInvolution