# Combining IIM and MZT transformation

Split from thread: Correcting Impulse Invariance Method

Back to this subject. Matt L suggested combining IIM and MZT b-coeffs to get the filter response improved at hihger frequency area.

Couldn't find suitable IIM (C++) implementation to use so, I'm still having some difficulties with calculating and combining coefficients. How's that done?

• What keeps you from implementing Eq. (5) of this answer? – Matt L. Apr 2 '16 at 10:01
• To be frank, my weak DSP/math skills --> I don't know the theory behind the filters/transformation/math --> what is needed to get the right answers nor what to expect as a right answer. – Juha P Apr 4 '16 at 13:19
• Do you know how to manipulate Eq. (5) such that you get one common numerator and one common denominator? Once you have the result in that form, the coefficients in the numerator are your $b$ coefficients, and the ones in the denominator are the $a$ coefficients. – Matt L. Apr 4 '16 at 14:00
• If you like you can contact me via my profile. Click on the website and you'll find an email address under 'About Me'. – Matt L. Apr 4 '16 at 14:09
• Thanks, now that you tipped what to do for the Eq. (5), I'll try to solve those by using Maxima (maxima.sourceforge.net/documentation.html). – Juha P Apr 4 '16 at 16:12