PVector  v = new PVector(10, 20, 0);
float d = v.dot(60, 80, 0);
println(d);  // Prints "2200.0"

PVector v1, v2;

void setup() {
  size(100, 100);
  v1 = new PVector(20.0, 30.0, 40.0);
  v2 = new PVector(0.0, 0.0, 0.0);
  v2.set(v1);
  println(v2.x);  // Prints "20.0"
  println(v2.y);  // Prints "30.0"
  println(v2.z);  // Prints "40.0"
}

PVector  v1 = new PVector(10, 20, 0);
PVector  v2 = new PVector(60, 80, 0); 
float d = v1.dot(v2);
println(d);  // Prints "2200.0"