The Power Method for Eigenvalues and Eigenvectors

POWER_METHOD, a C library which carries out the power method.

The power method seeks to determine the eigenvalue of maximum modulus, and a corresponding eigenvector.

The power method will not perform as expected if, corresponding to the maximum modulus, there are complex eigenvalues, or a pair of real eigenvalues of opposite sign. The power method's behavior can break down or be very slow initially if the starting vector has a zero or very small component in the eigenspace corresponding to the maximal eigenvalue.


The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.


POWER_METHOD is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version.

Related Data and Programs:


TEST_EIGEN, a C library which implements test matrices for eigenvalue analysis.

TEST_MAT, a C library which defines test matrices.


  1. Richard Burden, Douglas Faires,
    Numerical Analysis,
    Thomson Brooks/Cole, 2004,
    ISBN13: 978-0534392000,
    LC: QA297.B84.
  2. Ward Cheney, David Kincaid,
    Numerical Mathematics and Computing,
    Brooks-Cole Publishing, 2004,
    ISBN: 0534201121.
  3. Gene Golub, Charles VanLoan,
    Matrix Computations, Third Edition,
    Johns Hopkins, 1996,
    ISBN: 0-8018-4513-X,
    LC: QA188.G65.

Source Code:

Last modified on 27 July 2019.