# [PD] sonyfing this function with fexrp~

Mathieu Bouchard matju at artengine.ca
Thu Jan 13 18:02:59 CET 2011

```On Thu, 13 Jan 2011, ronni montoya wrote:

> Hi , i been trying to sonify the simplied version of the Lokta
> Volterra equation with fexpr~ but im not having any luck
> Can anybody point how to do this?
> Z(t + 1) =  Z(t) + cU(t) - V(t)

Any textbook I can find says the equation is instead :

x' = α*x - β*x*y
y' = δ*y - γ*x*y

(note the difference between lowercase gamma and y)

> If  Z(t) = 0 , U(t)  = 0.4  then V(t) = 0.5  and c = 0.5
> So after one step:
> Z(t + 1) =  0 + 0.5(0.4) (0.5) = 0.1

You're missing a minus sign according to your own equations, but also, I
don't think you can pick U and V to be whatever you like. I think that
they are supposed to be some equations in particular, but you didn't read
properly.

You also can't say that Z(t) = 0 at the same time as Z(t+1) = ... when t
is not being specified (what can this possibly mean other than "for any t"
?)

> Can anybody point me how to sonify this with fexpr~?

Please first figure out what is "this".

_______________________________________________________________________
| Mathieu Bouchard ---- tél: +1.514.383.3801 ---- Villeray, Montréal, QC
```