Curve fit for piecewise - Lazy evaluation (Defer / Hold?) on constraint passed to Minimize[]?

*To*: mathgroup at smc.vnet.net*Subject*: [mg119454] Curve fit for piecewise - Lazy evaluation (Defer / Hold?) on constraint passed to Minimize[]?*From*: Eric Cousineau <eacousineau at gmail.com>*Date*: Sat, 4 Jun 2011 06:21:52 -0400 (EDT)

Is there to defer / hold evaluation for a constraint passed to Minimize[]? I'm wondering because I want to ensure that a particular point on the curve fits as closely as possible to the given data, i.e., give it more weight at that point. Example: (sorry for some of the hackish things, coming to Mathematica from another system) param = {x0, a, b, c, ...}; xflat = ... yflat = ... x0index := Position[xflat, Nearest[xflat, x0][[1]]][[1]]; y0 := yflat[[x0index]][[1]] &; funcs = {{f[x], x < x0}, {g[x], x >= x0}}; model = Piecewise[funcs]; constraint := y0 == funcs[[1,1]] == funcs[[2,1]] /. x->x0; (*Not sure how to do lazy*) results = Minimize[{model, constraint}, param]; This code works without involving the y0 expression. Once that's involved, I get the error: NMinimize::bcons: The following constraints are not valid: ... Constraints should be equalities, inequalities, or domain specifications involving the variables. I've tried apply Defer[] and Hold[] just for kicks and giggles, but it didn't work.