Wednesday, May 23, 2012

Power Method

A is an n x n matrix.
Choose a starting vector u arbitrarily (usually components of vector all equal 1).

1.       Calculate Au
2.       Normalise resulting vector by dividing each component by the largest in magnitude.
3.       Repeat steps 1 and 2 until change in normalising factor is negligible.

Resulting normalising vector is the dominant eigenvalue and the final vector is the eigenvector.

Gerschgorin's Circle Theorem

Let A be an n x n matrix.
The circle in the complex plane is given by:
Eigenvalues of A are contained in the union of the circles.

Economizing a Power Series

where
refers to the n-th degree Chebyshev polynomial

Chebyshev Polynomials

Pade Approximation