User`s guide

R2014a
3-14
Mathematics
isdiag, isbanded, issymmetric, ishermitian, istril,
istriu, and bandwidth functions for testing matrix structure
The following functions test various aspects of matrix structure and are useful in
simplifying numerical algorithms.
• ishermitian determines if a matrix is Hermitian or skew-Hermitian.
• issymmetric determines if a matrix is symmetric or skew-symmetric.
• istriu determines if a matrix is upper-triangular.
• istril determines if a matrix is lower-triangular.
• isdiag determines if a matrix is diagonal.
• bandwidth returns the upper and lower bandwidth of a matrix.
• isbanded determines if a matrix is within the specified upper and lower bandwidths.
sylvester function for solving the Sylvester equation
The sylvester function solves the Sylvester equation, AX + XB = C, for X.
Option for eig function for computing left eigenvectors
The eig function can now calculate the left eigenvectors of a matrix A explicitly.
For example:
A = magic(3);
[V,D,W] = eig(A)
V =
-0.5774 -0.8131 -0.3416
-0.5774 0.4714 -0.4714
-0.5774 0.3416 0.8131
D =
15.0000 0 0