# Characteristic function of [0,1):
#   one(t) =  1, if 0=<t<1
#   one(t) =  0, otherwise
one <- function(t) {   # code to define the function "haar" follows:
  if(t>=0) {
    if(t<1) {
      return(1);
    }
  }
  return(0);
}

# Stationary subdivision:
ss <- function( h, n, t) {
  if(n<=0) return(one(t));
  out <- h;
  for(k in 1:length(h) ) {
    out[k] <- h[k]*ss(h,n-1,2*t-(k-1));
  }
  return(sqrt(2)*sum(out))
} 

# Plot the Daubechies 4 scaling function
depth <- 4;      # number of iterations from one()
numpts <- 100;   # number of points to plot

sr3 <- sqrt(3);
h<-c((1+sr3)/4, (3+sr3)/4, (3-sr3)/4, (1-sr3)/4); # D4 coefficients
d4 <- 1:numpts;
for(x in 1:numpts) d4[x] <- ss(h, depth, 3*x/numpts);
plot(d4, type="l")