Table 4.1 "Multivariable Feedback Control"

Dear Sigurd and Ian

I have just noticed an error on page 119 of your book.
In the matlab code for computing normalized coprime factorizations (see
Table 4.1), square roots of the PSD matrix R are required.

The code given in Table 4.1 invokes "sqrt(R)" which produces
element-by-element square roots - not what is required here.

I have always used the cholesky decomposition to find the required root,
but matlab also has a function "sqrtm" which is appropriate here.

So, you need to change "sqrt" to "sqrtm" for things to work properly.

The code as it stands will only produce a normalized factorization for
strictly proper plants.

Best regards,

Daniel

====================
Dr. D.J. Walker
Engineering Dept.
Leicester University
University Road
LEICESTER LE1 7RH, U.K.

Tel +44 (0)116 252 2529
Fax +44 (0)116 252 2619
Email: wjd@le.ac.uk
Received on Tue Nov 09 16:48:13 1999