RE: Q about NonlinearFit
- To: mathgroup@smc.vnet.net
- Subject: [mg11504] RE: [mg11441] Q about NonlinearFit
- From: Ersek_Ted%PAX1A@mr.nawcad.navy.mil
- Date: Fri, 13 Mar 1998 12:21:56 -0500
Sami wrote: ---------- |I need to use NonlinearFit for a set of data. The model is valid when |each of the 2 parameters (that I need to determine) is not equal to 1 |(indeterminate when parameters = 1). What is the best way to go about |evaluating the data ? | Does model[para1,para2] approach a value in the limit as (para1->1, para2->1). If this is the case use the value you get in the limit for the case where (para1=1) or (para2=1). Even if the limit is different from different directions you can pick a reasonable value for the case where (para1=1) or (para2=1). A one variable case where the limit exists: Your model is Sin[x]/x. In this case use model[x_]:= If[x!=0, Sin[x]/x, 1]. Sin[0]/0 is Indeterminate, but in the limit it's (1), so it works just fine. A one variable case where the limit doesn't exist: Your model is (x^x). You could use model[x_]:= If[x!=0, x^x, 1]. This way you get (model[0]:=1). (0^0)-is Indeterminate, but using (model[0]->1) is as good as anything else. Your example involves two parameters, but the above idea might get you started. Ted Ersek