MATLAB 6.1 Release Notes (MATLAB Release Notes)

MATLAB Release Notes

Mathematics Issues

Finding Smallest Magnitude Eigenvalues

eigs(A,k,sigma) and eigs(A,B,k,sigma) return k eigenvalues based on sigma. For sigma = 'sm', eigs returns the smallest magnitude eigenvalues.

In MATLAB 6.0, eigs was reimplemented to use the ARPACK library of routines. Unfortunately, the smallest magnitude case, sigma = 'sm' and sigma = 0, chose the wrong algorithm. For MATLAB 6.1, the correct ARPACK algorithm is used and convergence is much quicker.

This bug fix introduces a backwards incompatibility. When A is a function Afun and sigma = 'sm', Afun must now return Y = A\x. Prior to MATLAB 6.1, eigs required Afun to return y = A*x for this case.

Possible Changes in Results Returned by Matrix Functions

Starting in MATLAB 6.0 (R12.0), matrix computations are based on LAPACK, a large, multiauthor Fortran subroutine library for numerical linear algebra. While this change has many benefits and matrix functions continue to operate in the same way in MATLAB 6.0, the results returned by matrix functions may differ. Changes in roundoff errors can be seen in most matrix computations. In cases where quantities are not uniquely determined mathematically, results may differ in order and in normalization.

For example:

Eigenvalues may be returned in a different order.
Eigenvectors may be normalized differently.
The signs of columns of orthogonal matrices may differ.
rcond is a better estimate of the reciprocal condition.
lu can now be used to factor rectangular full matrices.

Obsolete Input Arguments

Certain input arguments to these functions have become obsolete. Using these arguments does not result in an error, but they are ignored.

Function
Description

delaunay
Now ignores the third argument fuzz, which specified a value for the fuzz standard deviation.
Now ignores the third argument 'sorted'. This argument indicated to delaunay that the given points x and y were sorted, and that duplicate points had been eliminated.

convhull
Now ignores the third argument TRI, which provided triangulation data previously computed using delaunay.

Function	Description
`delaunay`	Now ignores the third argument `fuzz`, which specified a value for the `fuzz` standard deviation. Now ignores the third argument `'sorted'`. This argument indicated to `delaunay` that the given points `x` and `y` were sorted, and that duplicate points had been eliminated.
`convhull`	Now ignores the third argument `TRI`, which provided triangulation data previously computed using `delaunay`.

Obsolete Functions

The following MATLAB function has become obsolete. For backwards compatibility, it has not been removed from the language at this time. However, this function may be removed in a future release, and you are encouraged to discontinue its use, or use the function that replaces it

.

Function
Description

bvpval
Evaluate the numerical solution of a boundary value problem (BVP). Replace with deval, which evaluates the solution of both initial value and boundary value differential equation problems.

Function	Description
`bvpval`	Evaluate the numerical solution of a boundary value problem (BVP). Replace with `deval`, which evaluates the solution of both initial value and boundary value differential equation problems.

Development Environment Issues Programming and Data Types Issues