diff options
Diffstat (limited to 'unsupported/Eigen/MatrixFunctions')
| -rw-r--r-- | unsupported/Eigen/MatrixFunctions | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/unsupported/Eigen/MatrixFunctions b/unsupported/Eigen/MatrixFunctions index ff466a519..0b12aaffb 100644 --- a/unsupported/Eigen/MatrixFunctions +++ b/unsupported/Eigen/MatrixFunctions @@ -264,7 +264,28 @@ where \f$ T_1 \f$ is invertible. Then \f$ T^p \f$ is given by \warning Fractional power of a matrix with a non-semisimple zero eigenvalue is not well-defined. We introduce an assertion failure -against inaccurate result, e.g. \include MatrixPower_failure.cpp +against inaccurate result, e.g. \code +#include <unsupported/Eigen/MatrixFunctions> +#include <iostream> + +int main() +{ + Eigen::Matrix4d A; + A << 0, 0, 2, 3, + 0, 0, 4, 5, + 0, 0, 6, 7, + 0, 0, 8, 9; + std::cout << A.pow(0.37) << std::endl; + + // The 1 makes eigenvalue 0 non-semisimple. + A.coeffRef(0, 1) = 1; + + // This fails if EIGEN_NO_DEBUG is undefined. + std::cout << A.pow(0.37) << std::endl; + + return 0; +} +\endcode Details of the algorithm can be found in: Nicholas J. Higham and Lijing Lin, "A Schur-Padé algorithm for fractional powers of a |