RE: Binomial eq..using FindRoot. Bug?
- To: mathgroup at smc.vnet.net
- Subject: [mg18061] RE: [mg17992] Binomial eq..using FindRoot. Bug?
- From: "J.Guillermo Sanchez" <guillerm at gugu.usal.es>
- Date: Tue, 15 Jun 1999 01:43:22 -0400
- Delivery-date: Tue Jun 15 07:43:19 1999
- References: <s75f9cdf.086@gwia.umsmed.edu>
- Sender: owner-wri-mathgroup at wolfram.com
I post an e-mail for the mathgroup and I have received very nice solution.
Thanks every body.
But I have a curiosity.
My equation was: Binomial[f n, r]/Binomial[n, r] == a.
If I resolve using FindRoot in the way,
h[n_,f_,a_]:= FindRoot[Binomial[f n, r]/Binomial[n, r] == a , {r, 20}];
h[320,0.95,0.05].
Out: {r->53.3465}, that is OK
but if I move Binomial[n, r] to other side (the eq. is the same):
g[n_,f_,a_]:= FindRoot[Binomial[f n, r] == a Binomial[n, r] , {r, 20}];
g[320,0.95,0.05].
I recived the message:
FindRoot::"cvnwt":
"Newton's method failed to converge to the prescribed accuracy after 15
iterations."
{r->14.5784} that is wrong.
It is a bug or are there any rules to use FindRoot that I didn't apply?.