HELP! Strange evaluations
- To: mathgroup at smc.vnet.net
- Subject: [mg33578] HELP! Strange evaluations
- From: "Lawrence A. Walker Jr." <lwalker701_remove_ at earthlink.net>
- Date: Mon, 1 Apr 2002 02:02:12 -0500 (EST)
- Organization: Morgan State University, COMSARE
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
For the life of me I can't figure out how to get the following to work
correctly. I also tried using various combinations of Hold and Evaluate
-- but to no avail.
<< Statistics`NonlinearFit`
(* This works ok *)
goo[a_, b_] :=
FindRoot[( Cos[a x]) == b x, {x, 0}][[1, 2]];
(* Here are some sample data *)
data = Table[{i, goo[i, .5]}, {i, 0, 1, .2}];
(* This doesn't work -- I expect b->.5 to be returned. *)
BestFitParameters /.
NonlinearRegress[data, goo[a, b], a, {b, {0., 1.}},
RegressionReport -> BestFitParameters]
After executing the above, I get the following error messages:
FindRoot::frnum: Function {0. b+Cos[0. a]} is not a length 1 list of
numbers at {x} = {0.}.
NonlinearRegress::nonnum: The model is not numerical at {b->0., a->0.}.
Check that all model parameters are included in the parameter list...
How do I get the above to work.