Responses for Box-Cox transformations

*To*: mathgroup at smc.vnet.net*Subject*: [mg23514] Responses for [mg23479] Box-Cox transformations*From*: David Alan Paul <david_alan_paul at yahoo.com>*Date*: Tue, 16 May 2000 02:45:00 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

The following are answers that have been given me in response to my query mg23479 regarding Box-Cox transformations. Thanks to both gentlemen for their advice! -David Paul FIRST RESPONSE: Dear David, Try this: fm[fun_, startv_, opts___] := Module[{vars = Table[Unique[], {Length[startv]}]}, FindMinimum[ fun[Sequence @@ vars], Evaluate[Sequence @@ MapThread[List, {vars, startv}]], opts]]; fun[a_,b_]:=Sin[a b]; fm[fun,{0.3,0.5}] fm does the same as FindMinimum, but takes a function symbol and a list of starting values instead of a Sequence of variable- startingValue pairs. Hope that helps. Of course, you could extend this Module in various directions. The simple idea is to generate a List of variables inside of the module and then to use MapThread to generate a Sequence of pairs of variables and starting values. The Evaluate is necessary, because FindMininum has Attribute HoldAll. Johannes Ludsteck Centre for European Economic Research (ZEW) Department of Labour Economics, Human Resources and Social Policy Phone (+49)(0)621/1235-157 Fax (+49)(0)621/1235-225 P.O.Box 103443 D-68034 Mannheim GERMANY Email: ludsteck at zew.de SECOND RESPONSE: Dear David Paul, What you have to do is to treat your variables and starting values as objects of their own. _Somewhere_ you have to specify them, e.g. as vars = {x, y, z}; (* these must be symbols without a value *) starts = {x0, y0, z0}; (* these are the starting points, substitute directly or give the x0,... a value respectively *) FindMinimum[function, ##] & @@ Transpose[{vars, starts}] FindMinimum::"fmns": "Starting value \!\(x0\) in \!\({x, x0}\) is not a real \number." (* the error was provoked to see the following: *) FindMinimum[function, {x, x0}, {y, y0}, {z, z0}] Kind regards, Hartmut Wolf Hartmut <hwolf at debis.com> ===== ___________________________ David Alan Paul <david_alan_paul at yahoo.com> ___________________________ __________________________________________________ Do You Yahoo!? Send instant messages & get email alerts with Yahoo! Messenger. http://im.yahoo.com/