print probability density function and a samples of the exponential distribution

sampleexp.pde

float sc;
float tau;

void setup(){
  size(500,500);
  smooth();
  strokeWeight(1);
  background(255);
  
  sc = height*10;
  tau = 0.02;
  
  for(int i=0; i<width; i++){
    line(i,height-sc*exp_pdf(i,tau),i+1,height-sc*exp_pdf(i+1,tau));
  }
  
  strokeWeight(0.01);
}


float exp_pdf(float x, float tau){
  return tau*exp(-tau*x);
}

float exp_sample(float tau){
  return -log(random(0,1))/tau;
}


void draw(){
  float x = exp_sample(tau);
  line(x,0,x,height);
}