Re: Function evaluation
- To: mathgroup at smc.vnet.net
- Subject: [mg17585] Re: Function evaluation
- From: "Peltio" <peltDOT.ioNOS at PAMiolDOT.it>
- Date: Mon, 17 May 1999 02:14:32 -0400
- Organization: Peltio Inc.
- References: <7hgdks$4c6@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
phpcp at csv.warwick.ac.uk wrote
>I have a function defined as
>
>f[s_,n_]:=BesselK[0,n*(1-s)]-BesselK[0,n]*BesselI[0,n*(1-s)]/BesselI[0,n]
>
>We can see that at s=0, f is zero. but mathematica returns a small number,
>i think it is the workingprecision. I have tried to change the working
>precision, but that does not help. the function still evaluates to a
>10^-16 number. I am using this function to define other functions. Ccan
>someone help me find a way to evaluate this function correctly.
To get rid of the approximation errors , you can use Chop
f[s_,n_]:=BesselK[0,n*(1-s)]-BesselK[0,n]*
BesselI[0,n*(1-s)]/BesselI[0,n] //Chop
Hope this helps,
Peltio