Re: test this in matlab for my please

[Doug Stewart]

Some good news I can now get the same results as Matab for all the test cases that

you men have tested for me.

If you want to see what I have learned read this. It isn'e polished but does record

the important points.

https://dl.dropboxusercontent.com/u/24993484/Z_tran%20_of_repeated_roots.pdf

I now have to rewrite my code to make it look better and then update the control pkg.

There is one difference from matlab and as such one question.

on this page:

http://www.mathworks.com/help/signal/ref/impinvar.html

matlab says;

"

Plot the digital impulse response, multiplying the numerator by a constant (Fs) to compensate for the 1/Fs gain introduced in the impulse response of the derived digital filter.

[b,a] = butter(4,0.3,'s'); 
[bz,az] = impinvar(b,a,10);
sys = tf(b,a);
impulse(sys);
hold on;
impz(10*bz,az,[],10);

"

Notice the 10*bz ;

Their code produces the filter coefficients  that are wrong by a factor of Fs!!!!

My code does not need this extra multiply by Fs.

What should I do?

To say it another way their output from the filter needs a correction factor!

I would prefer to keep my results. It is derived with proper math.

Doug