curve() using a function with argument in R-CodePudding

ppt=function(v, tail = 0.5){
  if (tail == 1){
    6/pi^2/v^2
  } else {
    if (v < 11) {
      (1-tail)*(11-v)/55
      } else {tail*6/pi^2/(v-10)^2}
  }
}
curve(ppt(tail = 0.2))
Error in curve(ppt(tail = 0.2)) : 
  'expr' must be a function, or a call or an expression containing 'x'

How should I plot a smooth curve for the function ppt() with different values of variable tail?

Thank you.

CodePudding user response：

Either (1) rewrite ppt to vectorize it (not shown) or else (2) use Vectorize as shown below in which case ppt does not have to be modified. Also use this syntax.

curve(Vectorize(ppt)(x, tail = 0.2), ylab = "ppt")

CodePudding user response：

Maybe the following trick?

w = 0.2
g <- function(z) ppt(z, tail = w)
curve(g)

And do not forget to replace, as @MrFlick points out in the comment:

if (v < 11) {
      (1-tail)*(11-v)/55
      } else {tail*6/pi^2/(v-10)^2}

ifelse(v < 11, (1-tail)*(11-v)/55, tail*6/pi^2/(v-10)^2)