DummyMath Benchmark

globals [ result ]

to benchmark
  set result 0.0
  random-seed 362
  reset-timer
  setup
  repeat 100000 [ go ]
  set result timer
end 

to setup
  ca
end 

;; I ripped the math out of the collide procedure from the GasLab New Benchmark. ~Forrest (6/06/2006)

to go

  ;;; PHASE 1: initial setup
  let mass1 2.0 + random-float 10.0
  let speed1 2.0 + random-float 10.0
  let heading1 random-float 360

  let mass2 2.0 + random-float 10.0
  let speed2 2.0 + random-float 10.0
  let heading2 random-float 360

  ;; since particles are modeled as zero-size points, theta isn't meaningfully
  ;; defined. we can assign it randomly without affecting the model's outcome.
  let theta (random-float 360)

  ;;; PHASE 2: convert velocities to theta-based vector representation

  ;; now convert my velocity from speed/heading representation to components
  ;; along theta and perpendicular to theta
  let v1t (speed1 * cos (theta - heading1))
  let v1l (speed1 * sin (theta - heading1))

  ;; do the same for other-particle
  let v2t (speed2 * cos (theta - heading2))
  let v2l (speed2 * sin (theta - heading2))



  ;;; PHASE 3: manipulate vectors to implement collision

  ;; compute the velocity of the system's center of mass along theta
  let vcm (((mass1 * v1t) + (mass2 * v2t)) / (mass1 + mass2) )

  ;; now compute the new velocity for each particle along direction theta.
  ;; velocity perpendicular to theta is unaffected by a collision along theta,
  ;; so the next two lines actually implement the collision itself, in the
  ;; sense that the effects of the collision are exactly the following changes
  ;; in particle velocity.
  set v1t (2 * vcm - v1t)
  set v2t (2 * vcm - v2t)

  ;;; PHASE 4: convert back to normal speed/heading

  ;; now convert my velocity vector into my new speed and heading
  set speed1 sqrt ((v1t * v1t) + (v1l * v1l))
  let energy1 (0.5 * mass1 * speed1 * speed1)
  ;; if the magnitude of the velocity vector is 0, atan is undefined. but
  ;; speed will be 0, so heading is irrelevant anyway. therefore, in that
  ;; case we'll just leave it unmodified.
  if v1l != 0 or v1t != 0
    [ set heading1 (theta - (atan v1l v1t)) ]

  ;; and do the same for other-particle
  set speed2 sqrt ((v2t * v2t) + (v2l * v2l))
  let energy2 (0.5 * mass2 * speed2 * speed2)
  if v2l != 0 or v2t != 0
    [ set heading2 (theta - (atan v2l v2t)) ]
end