Hi:
There, I've got a question about how to read in expressions as function
parameters and it really bothered me.
I'm going to use curve() function to plot curves, and I'd like to write a
menu function to let use input math expressions.
say, if I'd like curve(3*x*x-4/x, 10, 100), I use scan() to read in the
math expression
form<- scan(file = "", what = character(0), n=1,strip.white =
TRUE,quiet=TRUE )
then get form as a string. "3*x*x-4/x"
Use parse() to convert it into expression
form2<-parse(text=form)
then form2=expression(3*x*x-4/x).
However, curve(form2,10,100) doesn't work at all.
Is there anyway to get this done?
Thanks a lot!
Alex
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