Plotting function with specific values

Question

I would want to draw a plot of an function that

if 0< x< 0.5, f(x)= 0.5(x)^3*(1-x)^6

if 0.5≤ x< 1 , f(x)= 1.5(x)^3*(1-x)^6

if x=0 or x=1, f(x)=0.

How could I do this?

Answer 1

Here is a function that is fully vectorized and returns NA outside the interval [0, 1]. It utilizes that logical values are coerced to 0/1 in arithmetic operations and that anything to the power of zero is one.

foo <- function(x) ((x > 0 & x < 0.5) * 0.5 * x ^ 3 * (1 - x) ^ 6 + 
  (x >= 0.5 & x < 1) * 1.5 * x ^ 3 * (1 - x) ^ 6) * NA ^ (x < 0 | x > 1) 

curve(foo(x), -0.1, 1.1)

Answer 2

If possible it is better to use a vector input to the function:

foo <- function(x) ifelse(x>0 & x<0.5,  0.5*x^3 *(1-x)^6, 1.5*x^3 *(1-x)^6)

plot(foo, from=-0.1, to=1.1)

Answer 3

myf=function(x) {
  if (x>0 & x<0.5) {
    return(0.5*x^3*(1-x)^6)
  } else if (x>=0.5 & x<1) {
    return(1.5*x^3*(1-x)^6)
  } else {
    return(0)
  }
}

myrange=seq(0,1,0.01)
plot(y=sapply(myrange,myf),x=myrange,type="l")