50g

Hi

I don't understand the result with inverse Z transform, for example with this equation:

X(z)=1/((z-1)²*z²)

The result is:
x(k)=2.d(k-1)+d(k-1)-2.1(k-1)+(k-1).1(k-1) Where d is Dirac.

But Neoploys return:
x(k)=-2.1^(k-1)+(k-1).1^(k-2)

Where are Dirac, and why the last is (k-2) ?!?

Second example:
X(z)=(z²+z+2)/((z-1)(z²-z+1))

I fund Cos and Sin in the result.
But the HP return complex, so I don't know how "translate" it...

Thanks a lot for your help.

Nico