如何编写R函数

Question

My attempt is below- I don't know how to create my function in a way where my first element will be π and my second element lambda. Any help would be great.

F<- function(y){ exp(-y)/(sqrt(2*pi*y))}

prob<-function(y, lambda)
  {(lambda^y) / (F(y)*1-exp(-lambda))}

Answer 1

If I understood correctly You are missing if/else in your function.

prob<-function(y, lambda)
{ if(y==0)
{
  return(pi)
} else {
  return((lambda^y) / (F(y)*1-exp(-lambda)))
}
  }

When y is equal 0 it returns pi otherwise formula you wrote