strange s-domain co-efficients like " 1400s + 7943000

Hello!

I obtained following TF from the Frequency response of a controller and put in the feedback to verify. Output is according to expected but the co-efficients are very strange as below:

1450 s + 7.943e05
-------------------------
s^2 + 203.6 s - 9.588e-05

I would like to convert this to z-domain using c2z and later i have to get the VHDL code using HDL coder.

Can I still use these co-efficients to proceed.

Thanks

Answer 1

[Walter Roberson]

Give the command

format long g

before displaying the coefficients.

[Safiya]

Thank you for reply , i understand ,, but I would like to ask, if this kind of large numbers (co-efficients) converted to discrete domain and later HDL code. what does these numbers will effect on accuracy and chip area. Thanks

[Walter Roberson]

It might have an effect on accuracy, but not necessarily on chip area. You would be using the Fixed Point Toolbox to create an evaluation scheme, and the area required for that is going to depend in part on the length of the words you design in.

If you indicate the s range you are interested in, and the accuracy of result you desire, I could try to figure out how many bits you would need to achieve that accuracy.

Keep in mind that it has poles at -203.6000005 and +4.709233781*10^(-7) so if those are in your range then you need to indicate how big your want your "infinity' to be.