(Sorry if this reply appears twice - 1st one disappeared?)
This worked for me: -
H, p, Pole1, Pole2, Pole3, Ts, z, f = var("H p Pole1 Pole2 Pole3 Ts z
f")
p = (2/Ts)*(z-1)/(z+1)
z = exp(I*2*pi*Ts*f)
H = (p^3)/((p-Pole1)*(p-Pole2)*(p-Pole3))
show(H)
The only difference is that I have declared the variables in the first
line. Hope that helps.
On Dec 8, 5:58 pm, Sand Wraith <[EMAIL PROTECTED]> wrote:
> Hi all! Please help me to replace variables:
>
> I have this function:
>
> H(p)=(p^3)/((p-Pole1)*(p-Pole2)*(p-Pole3))
>
> where Pole1,Pole2,Pole3 - complex:
>
> r=2*2*pi
> Pole1=r*exp(I*2*pi/3)
> Pole2=-r
> Pole3=r*exp(-I*2*pi/3)
> Ts=0.1
>
> And I need to make a few replaces:
>
> need to replace "p" with "(2/Ts)*(z-1)/(z+1)", where z is a new
> variable, and then replace "z" with "exp(I*2*pi*Ts*f)". To have H(f)
> function at the end.
>
> I am trying to write:
>
> z=exp(I*2*pi*Ts*f)
> p=(2/Ts)*(z-1)/(z+1)
> H=(p^3)/((p-Pole1)*(p-Pole2)*(p-Pole3))
>
> and now if I want to look at H:
> H
> or
> show(H)
> I've got many errors...
>
> tail of long output:
>
> <sage-display>
> stdin:16:Incorrect syntax: Syntax error
> _tmp_ : (8000.0(
> ^
> <sage-display>(%o90)
>
> what is wrong with it?
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