[R] Function with upper/lower bound, shift,slope,curvature
Tolga Uzuner
tolga at coubros.com
Mon Jun 26 12:35:51 CEST 2006
Dear R Users,
I am looking for a function to use within optim s.t.
- f(x,a,b,c,d,e) where I am searching over parameter values a,b,c,d,e
- a is the lower bound (typically 1)
- b is the upper bound (typically 0)
- c,d,e give the function a shift, slope and curvature between a and b
Any good candidates for a non-linear optimisation problem known, either
already built into R, or otherwise.
A sigmoid sort of gets half there, but I need some more control over the
curvature and upper/lower bounds of the function.
sigm<-function(x,a,t) 0.5*(1+(1-exp((x-a)/t))/(1+exp((x-a)/t)))
Thanks in advance,
Tolga
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