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##

Modification of `do`

One of the last steps `do` does is finding an unitary transformation
matrix that transforms the (by that time diagonalized)
*K*
and
*W*
matrices into a form that is not diagonal but has equal diagonal entries.
This unitary transformation matrix is not unique and therefore the optimal
filter that is found is not unique. Two different methods to find this
matrix are implemented. Default is the method of Hwang [3] that
is guaranteed to terminate in a finite number of steps. The method of
Mullis and Roberts [2] is iterative and in some cases can need
much computing time before convergence, but sometimes more elegant filter
structures are found. This method is chosen if the variable `itmax`
is chosen greater than zero. This variable then specifies the maximum number
of iterations allowed for this method. If no convergence takes place within
the specified number of iterations, an error message is issued.

2009-06-03