Run tests, where possible, on user objective function
fnchk checks a user-provided R function, ffn.
fnchk(xpar, ffn, trace=0, ... )
xpar |
the (double) vector of parameters to the objective funcion |
ffn |
a user-provided function to compute the objective function |
trace |
set >0 to provide output from fnchk to the console, 0 otherwise |
... |
optional arguments passed to the objective function. |
fnchk attempts to discover various errors in function setup in user-supplied
functions primarily intended for use in optimization calculations. There are always
more conditions that could be tested!
The output is a list consisting of list(fval=fval, infeasible=infeasible, excode=excode, msg=msg)
fval |
The calculated value of the function at parameters |
infeasible |
FALSE if the function can be evaluated, TRUE if not. |
excode |
An exit code, which has a relationship to |
msg |
A text string giving information about the result of the function check: Messages and
the corresponding values of
|
John C. Nash <nashjc@uottawa.ca>
# Want to illustrate each case.
# Ben Bolker idea for a function that is NOT scalar
# rm(list=ls())
# library(optimx)
sessionInfo()
benbad<-function(x, y){
# y may be provided with different structures
f<-(x-y)^2
} # very simple, but ...
y<-1:10
x<-c(1)
cat("fc01: test benbad() with y=1:10, x=c(1)\n")
fc01<-fnchk(x, benbad, trace=4, y)
print(fc01)
y<-as.vector(y)
cat("fc02: test benbad() with y=as.vector(1:10), x=c(1)\n")
fc02<-fnchk(x, benbad, trace=1, y)
print(fc02)
y<-as.matrix(y)
cat("fc03: test benbad() with y=as.matrix(1:10), x=c(1)\n")
fc03<-fnchk(x, benbad, trace=1, y)
print(fc03)
y<-as.array(y)
cat("fc04: test benbad() with y=as.array(1:10), x=c(1)\n")
fc04<-fnchk(x, benbad, trace=1, y)
print(fc04)
y<-"This is a string"
cat("test benbad() with y a string, x=c(1)\n")
fc05<-fnchk(x, benbad, trace=1, y)
print(fc05)
cat("fnchk with Rosenbrock\n")
fr <- function(x) { ## Rosenbrock Banana function
x1 <- x[1]
x2 <- x[2]
100 * (x2 - x1 * x1)^2 + (1 - x1)^2
}
xtrad<-c(-1.2,1)
ros1<-fnchk(xtrad, fr, trace=1)
print(ros1)
npar<-2
opros<-list2env(list(fn=fr, gr=NULL, hess=NULL, MAXIMIZE=FALSE, PARSCALE=rep(1,npar), FNSCALE=1,
KFN=0, KGR=0, KHESS=0, dots=NULL))
uros1<-fnchk(xtrad, fr, trace=1)
print(uros1)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.