how to plot impulse response function

hello everyone, i have reach this function by using bilinear transformation and i need to plot magnitude, phase and impulse response, so i used matlab to get inverse z-transform and after transforming i get this complex function:

symsum((494712363027635506830*r3*r3^n + 152672243540641916325*r3^n - 1428757254008094624750*r3^n*r3^2 + 777668855400926329284*r3^n*r3^3)/(189906924395830620192768*r3^3 - 467221439741924737024000*r3^2 + 362426639580685381140480*r3 - 81453904300473738854400), r3 in root(z1^4 - (82359*z1^3)/25000 + (1621*z1^2)/400 - (20957*z1)/10000 + 1413/4000, z1)) + (98358615861771625*kroneckerDelta(n, 0))/8484781697966014464

and when trying to draw it using fvtool i get error message:

"FVTool does not accept sym as inputs."

the orginal function in z domain is:

F = (0.004095*(z^4-2*z^2+1))/(z^4-3.29436*z^3+4.0525*z^2-2.0957*z+0.35325)

, any help please

Answer 1

[Paul]

If all that's needed is a plot of the impulse response, as opposed to a closed from expression for it, then there is no need to use the Symbolic Math stuff. Just use tf and impulse() from the Control Systems Toolbox

doc tf
doc impulse

[Ibrahim Mohamed]

ok i will try, thank you very much