how do i use Finite Element Method with z-transform

I need to use digits and vpa to solve z funtion Frequency responses of the magnitude for filters

Answer 1

[nick]

Hi peter,

From your question, I understand that you are looking to solve the given transfer function using the "vpa" function.

You can define z as a symbolic variable using "syms" function and then simplify the expression with the "simplify" function, as shown in the code snippet below:

syms z 
H2 = vpa(0.216 + 0.0433*z^(-1) + 0.2201*z^(-2))/vpa(1+0.1075*z^(-1)+0.9796*z^(-2)) + ...
    vpa(0.216 - 0.0433*z^(-1) + 0.2201*z^(-2))/vpa(1-0.1075*z^(-1)+0.9796*z^(-2)) + ...
    vpa(0.216 + 0.0240*z^(-1) + 0.3036*z^(-2))/vpa(1+0.0865*z^(-1)+0.8929*z^(-2)) + ...
    vpa(0.216 - 0.0240*z^(-1) + 0.3036*z^(-2))/vpa(1-0.0865*z^(-1)+0.8929*z^(-2));
HVpa = simplify(H2)

HVpa = 

You may refer to the following documentation to learn more about "syms" and "simplify" functions:

https://www.mathworks.com/help/symbolic/simplify-symbolic-expressions.html

https://www.mathworks.com/help/symbolic/syms.html

Hope this helps