绒毛的吸收

globals [
  tick-advance-amount               ; how much we advance the tick counter this time through
  max-tick-advance-amount           ; the largest tick-advance-amount is allowed to be
  init-avg-speed init-avg-energy    ; initial averages

  particle-size
  toggle-red-state
  toggle-green-state
  min-particle-energy
  max-particle-energy
  particles-to-add
  show-wall-hits?
  max-particles
  #particles
  #-green-particles
  #-purple-particles
  #-orange-particles
  villi-slider-moved?
  old-villi-slider-value
  bottom-wall-ycor
  tracker-init-particles
  permeability
  particle-to-watch
  total-initial-particles
  total-absorbed-particles
]


breed [ particles particle ]
breed [ flows flow ]
breed [ walls wall ]
breed [ edges edge ]



particles-own [
  speed mass energy          ; particles info
  last-collision
  color-type
  absorbed?
  swept?
  large?
]

patches-own [
  is-blood?
  blood-heading

]


walls-own [
  energy
  valve-1?
  valve-2?
  pressure?
  surface-energy
]

to setup
  clear-all
  reset-ticks
  ask patches [set pcolor white]
  set particle-size 2
  set max-tick-advance-amount 0.02
  set show-wall-hits? false
  set particles-to-add 2
  set old-villi-slider-value 绒毛-高度
  set villi-slider-moved? true
  set bottom-wall-ycor min-pycor + 3
  set-default-shape walls "cell"


  set tracker-init-particles 初始-小的-食物微粒
  set permeability 50
  set particle-to-watch nobody


  redraw-villi?
  draw-blood-stream
  draw-edges
  make-small-particles
  make-large-particles
  set  total-initial-particles count particles
  set  total-absorbed-particles 0



  do-plotting
end 

to go

  if ticks < 模型结束在 [
  redraw-villi?

    ask particles with [not absorbed?] [ bounce ]
    ask flows [move-flows]
    ask particles with [not absorbed?] [ move ]
    ask particles with [absorbed?  and pycor != min-pycor] [seep-toward-blood]
    ask particles with [swept?] [sweep-with-blood]
  ;  ask particles with [not absorbed?] [ check-for-collision ]
    ask particles with [not absorbed? and any? walls-here ] [ rewind-to-bounce ]
    ask particles with [not absorbed? and any? walls-here ] [ remove-from-walls ]

    check-watched-particle

  tick-advance tick-advance-amount
  calculate-tick-advance-amount
  check-particle-flow-out-of-system


  do-plotting
  display
  ]
end 

to check-watched-particle
  if particle-to-watch != nobody [
  ask particle-to-watch [
      if pycor = max-pycor [rp]
    ]

    ]
end 

to check-particle-flow-out-of-system
  ask particles [
    if pxcor = max-pxcor and visualize-food-in-blood-flow-as = "going someplace else" [set total-absorbed-particles total-absorbed-particles + 1 set hidden? true]
  ]
end 

to watch-a-particle
  set particle-to-watch one-of particles with [pycor < (max-pycor - 2)]
  if count particles > 0 [
    watch one-of particles

  ]
end 


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;BUILD VILLI   ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

to shove-particles
  ask particles-here with [pycor <= (bottom-wall-ycor + 绒毛-高度)] [set ycor (bottom-wall-ycor + 绒毛-高度)]
end 

to add-wall
  shove-particles
          sprout 1 [
          set breed walls set color gray
          ;set is-blood? false
          initialize-this-wall
        ]
end 

to add-hidden-wall
  shove-particles
          sprout 1 [
          set breed walls set color gray
          set is-blood? false
          set hidden? true
          initialize-this-wall
        ]
end 

to initialize-blood
          set breed walls set color red
          set size 1.0
          set is-blood? true
          set heading 90
          set shape "square"
          set color [255 0 0 150]
end 

to add-blood-up
  shove-particles
  set blood-heading 0
  set is-blood? true
  sprout 1 [initialize-blood ]
end 

to add-blood-down
  shove-particles
  set blood-heading 180
  set is-blood? true
  sprout 1 [initialize-blood]
end 

to add-blood-right
  shove-particles
  set blood-heading 90
  set is-blood? true
  sprout 1 [initialize-blood]
end 

to redraw-villi?
  if old-villi-slider-value != 绒毛-高度 [set villi-slider-moved? true set old-villi-slider-value 绒毛-高度]
  if villi-slider-moved? [
     redraw-villi
     set villi-slider-moved? false
  ]
end 

to redraw-villi
  ask walls with [pycor >= (min-pycor + 3)] [die]
  ask patches with [pycor >= (min-pycor + 3)] [set is-blood? false]
   ;; draw horizontal line until reaching a point where a villi is... then call villi build...skip and continue

   let distance-between-villi 5

    ask patches with [pxcor >= min-pxcor and pxcor <= max-pxcor and pycor = max-pycor ]  [add-hidden-wall]


     let this-pxcor min-pxcor
     let this-pycor bottom-wall-ycor
     let villi-width 5
     let this-width-counter 0
     let this-lift false
   repeat (max-pxcor - min-pxcor + 1)  [

    ifelse ((this-pxcor mod 11 >= 0) and (this-pxcor mod 11 <= 4)) and (this-pxcor >= (min-pxcor + 3) and this-pxcor <= (max-pxcor - 5))
         [set this-pycor (bottom-wall-ycor + 绒毛-高度) set this-lift true]
         [set this-pycor bottom-wall-ycor]
    ask patches with [pxcor = this-pxcor and pycor = this-pycor] [add-wall]

    ;; draw-vertical wall
    if this-lift [
        ask patches with [pxcor = this-pxcor and pycor >= bottom-wall-ycor and pycor <= this-pycor] [
          if (this-pxcor mod 11 = 0 and pycor < (this-pycor)) [add-wall]
          if (this-pxcor mod 11 = 1 and pycor < (this-pycor - 1)) [add-blood-up]
          if (this-pxcor mod 11 = 2 and pycor < (this-pycor - 2))[add-wall]
          if ((this-pxcor mod 11 = 2 or this-pxcor mod 11 = 1) and (pycor = (this-pycor - 1) ))[add-blood-right]
         if ((this-pxcor mod 11 = 2 ) and ( pycor = (this-pycor - 2)))[add-blood-right]
          if (this-pxcor mod 11 = 3 and pycor <= (this-pycor - 1)) [add-blood-down]
          if (this-pxcor mod 11 = 4 and pycor < (this-pycor)) [add-wall]
        ]
      set this-lift false
      ]
    set this-pxcor this-pxcor + 1
   ]
end 

to draw-blood-stream
  let blood-patches patches with [pxcor >= min-pxcor and pxcor <= max-pxcor and pycor < bottom-wall-ycor and pycor >= min-pycor ]
  ask blood-patches [add-blood-right]
  ask n-of 30 blood-patches [
    make-a-floater
  ]
end 

to make-a-floater
  let this-color (5 + random-float 20)
  let this-list [0 0 0]
  set this-list lput  this-color this-list
  sprout 1 [
    set breed flows
  set color this-list
  set shape "square"
  ]
end 

to draw-edges
  ask patches with [pycor = (max-pycor) and pxcor < max-pxcor ][
    sprout 1 [
      set breed edges
      set shape "square 3"
      set size 1.05
      set color gray + 2
    ]
  ]
   ask patches with [pycor < (max-pycor) and pxcor = max-pxcor ][
    sprout 1 [
      set breed edges
      set shape "square 4"
      set size 1.05
      set color gray + 2
    ]
  ]
     ask patches with [pycor =(max-pycor) and pxcor = max-pxcor ][
     sprout 1 [
      set breed edges
      set shape "square"
      set size 1.05
      set color gray + 2
    ]
  ]
end 



;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;WALL INTERACTION;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;



;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;GAS MOLECULES MOVEMENT;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

to bounce  ; particles procedure
  ; get the coordinates of the patch we'll be on if we go forward 1
  let bounce-patch nobody
  let bounce-patches nobody
  let hit-angle 0
  let this-patch patch-here
  let new-px 0
  let new-py 0
  let visible-wall nobody

  set bounce-patch  min-one-of walls in-cone ((sqrt (2)) / 2) 180 with [ patch-here != this-patch ] [ distance myself ]

  if bounce-patch != nobody [
    set new-px [ pxcor ] of bounce-patch
    set new-py [ pycor ] of bounce-patch
    set visible-wall walls-on bounce-patch

    if any? visible-wall  [
      ifelse (random 100 > permeability or (pycor >= (max-pycor - 1) ) or large? ) [
      if bounce-patch != patch-here [ set hit-angle towards bounce-patch ] ;; new bounce patch code
      ifelse (hit-angle <= 135 and hit-angle >= 45) or (hit-angle <= 315 and hit-angle >= 225) [
        set heading (- heading)
      ][
        set heading (180 - heading)
      ]

      set absorbed? false]
      [set absorbed? true]
    ]


  ]
end 

to rewind-to-bounce  ; particles procedure
  ; attempts to deal with particle penetration by rewinding the particle path back to a point
  ; where it is about to hit a wall
  ; the particle path is reversed 49% of the previous tick-advance-amount it made,
  ; then particle collision with the wall is detected again.
  ; and the particle bounces off the wall using the remaining 51% of the tick-advance-amount.
  ; this use of slightly more of the tick-advance-amount for forward motion off the wall, helps
  ; insure the particle doesn't get stuck inside the wall on the bounce.

  let bounce-patch nobody
  let bounce-patches nobody
  let hit-angle 0
  let this-patch nobody
  let new-px 0
  let new-py 0
  let visible-wall nobody

  bk (speed) * tick-advance-amount * .49
  set this-patch  patch-here

  set bounce-patch  min-one-of walls in-cone ((sqrt (2)) / 2) 180 with [ self != this-patch ] [ distance myself ]

  if bounce-patch != nobody [

    set new-px [pxcor] of bounce-patch
    set new-py [pycor] of bounce-patch
    set visible-wall walls-on bounce-patch

    if any? visible-wall with [not hidden?] [
      set hit-angle towards bounce-patch

      ifelse (hit-angle <= 135 and hit-angle >= 45) or (hit-angle <= 315 and hit-angle >= 225) [
        set heading (- heading)
      ][
        set heading (180 - heading)
      ]


    ]
  ]
  fd (speed) * tick-advance-amount * 0.75
end 

to move  ; particles procedure
  if patch-ahead (speed * tick-advance-amount) != patch-here [ set last-collision nobody ]
  ifelse (not large?) [rt random 30 lt random 30][rt random 10 lt random 10]
  fd (speed * tick-advance-amount * 0.75)
  if ycor >  (bottom-wall-ycor + 绒毛-高度) [set xcor xcor - .05]
end 

to move-flows
  set heading 90
  fd (7 * tick-advance-amount * 0.75)
end 

to seep-toward-blood
  let flex-threshold .2 + random-float .05
  let all-blood patches with [is-blood?]
  let target-blood-patch min-one-of all-blood [distance myself  ]
 ; show distance target-blood
  let final-heading towards target-blood-patch
  let heading-difference ((final-heading - heading) / 20)
  set heading heading + heading-difference
  let blood-near-me all-blood with [distance myself < flex-threshold]
  ifelse not any? blood-near-me [fd (2 * tick-advance-amount) ][set swept? true]
end 

to sweep-with-blood
  let old-heading heading
  let heading-difference ((old-heading - heading) / 20)
  if (is-blood? and swept?)  [set heading blood-heading fd (3 * tick-advance-amount) set heading heading + heading-difference]
end 

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;GAS MOLECULES COLLISIONS;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;from GasLab

to calculate-tick-advance-amount
  ; tick-advance-amount is calculated in such way that even the fastest
  ; particles will jump at most 1 patch delta in a ticks tick. As
  ; particles jump (speed * tick-advance-amount) at every ticks tick, making
  ; tick delta the inverse of the speed of the fastest particles
  ; (1/max speed) assures that. Having each particles advance at most
  ; one patch-delta is necessary for it not to "jump over" a wall
  ; or another particles.
  ifelse any? particles with [ speed > 0 ] [
    set tick-advance-amount min list (1 / (ceiling max [speed] of particles )) max-tick-advance-amount
  ][
    set tick-advance-amount max-tick-advance-amount
  ]
end 

to check-for-collision  ; particles procedure
  ; Here we impose a rule that collisions only take place when there
  ; are exactly two particles per patch.  We do this because when the
  ; student introduces new particles from the side, we want them to
  ; form a uniform wavefront.
  ;
  ; Why do we want a uniform wavefront?  Because it is actually more
  ; realistic.  (And also because the curriculum uses the uniform
  ; wavefront to help teach the relationship between particles collisions,
  ; wall hits, and pressure.)
  ;
  ; Why is it realistic to assume a uniform wavefront?  Because in reality,
  ; whether a collision takes place would depend on the actual headings
  ; of the particles, not merely on their proximity.  Since the particles
  ; in the wavefront have identical speeds and near-identical headings,
  ; in reality they would not collide.  So even though the two-particles
  ; rule is not itself realistic, it produces a realistic result.  Also,
  ; unless the number of particles is extremely large, it is very rare
  ; for three or  particles to land on the same patch (for example,
  ; with 400 particles it happens less than 1% of the time).  So imposing
  ; this additional rule should have only a negligible effect on the
  ; aggregate behavior of the system.
  ;
  ; Why does this rule produce a uniform wavefront?  The particles all
  ; start out on the same patch, which means that without the only-two
  ; rule, they would all start colliding with each other immediately,
  ; resulting in much random variation of speeds and headings.  With
  ; the only-two rule, they are prevented from colliding with each other
  ; until they have spread out a lot.  (And in fact, if you observe
  ; the wavefront closely, you will see that it is not completely smooth,
  ; because  collisions eventually do start occurring when it thins out while fanning.)

  if count other particles-here  in-radius 1 = 1 [
    ; the following conditions are imposed on collision candidates:
    ;   1. they must have a lower who number than my own, because collision
    ;      code is asymmetrical: it must always happen from the point of view
    ;      of just one particles.
    ;   2. they must not be the same particles that we last collided with on
    ;      this patch, so that we have a chance to leave the patch after we've
    ;      collided with someone.
    let candidate one-of other particles-here with [ who < [ who ] of myself and myself != last-collision ]
    ;; we also only collide if one of us has non-zero speed. It's useless
    ;; (and incorrect, actually) for two particles with zero speed to collide.
    if (candidate != nobody) and (speed > 0 or [ speed ] of candidate > 0) [
      collide-with candidate
      set last-collision candidate
      ask candidate [ set last-collision myself ]
    ]
  ]
end 

; implements a collision with another particles.
;
; THIS IS THE HEART OF THE particles SIMULATION, AND YOU ARE STRONGLY ADVISED
; NOT TO CHANGE IT UNLESS YOU REALLY UNDERSTAND WHAT YOU'RE DOING!
;
; The two particles colliding are self and other-particles, and while the
; collision is performed from the point of view of self, both particles are
; modified to reflect its effects. This is somewhat complicated, so I'll
; give a general outline here:
;   1. Do initial setup, and determine the heading between particles centers
;      (call it theta).
;   2. Convert the representation of the velocity of each particles from
;      speed/heading to a theta-based vector whose first component is the
;      particle's speed along theta, and whose second component is the speed
;      perpendicular to theta.
;   3. Modify the velocity vectors to reflect the effects of the collision.
;      This involves:
;        a. computing the velocity of the center of mass of the whole system
;           along direction theta
;        b. updating the along-theta components of the two velocity vectors.
;   4. Convert from the theta-based vector representation of velocity back to
;      the usual speed/heading representation for each particles.
;   5. Perform final cleanup and update derived quantities.

to collide-with [ other-particles ] ;; particles procedure
  ; PHASE 1: initial setup

  ; for convenience, grab  quantities from other-particles
  let mass2 [ mass ] of other-particles
  let speed2 [ speed ] of other-particles
  let heading2 [ heading ] of other-particles

  ; 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 (speed * cos (theta - heading))
  let v1l (speed * sin (theta - heading))

  ;; do the same for other-particles
  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 (((mass * v1t) + (mass2 * v2t)) / (mass + mass2) )

  ; now compute the new velocity for each particles 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 particles 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 speed sqrt ((v1t ^ 2) + (v1l ^ 2))
  set energy (0.5 * mass * speed ^ 2)
  ; 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 heading (theta - (atan v1l v1t)) ]

  ;; and do the same for other-particle
  ask other-particles [
    set speed sqrt ((v2t ^ 2) + (v2l ^ 2))
    set energy (0.5 * mass * (speed ^ 2))
    if v2l != 0 or v2t != 0 [ set heading (theta - (atan v2l v2t)) ]
  ]
end 


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;  initialization procedures
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

to initialize-this-wall
;  set valve-1? false
 ; set valve-2? false
;  set pressure? false
  ifelse random 2 = 0 [set shape "cell"][set shape "cell2"]
  set color [255 255 255 120]
  let turn random 4
  rt (turn * 90)
end 

to make-small-particles
  create-particles 初始-小的-食物微粒 [
    setup-particles false
    set shape "small-molecule"
    random-position
  ]
end 

to make-large-particles
  create-particles 初始-大的-食物微粒 [
    setup-particles true
    set shape "large-molecule"
    random-position
  ]
end 

to setup-particles  [is-large]; particles procedure
 ; set shape "circle"
  set size particle-size
  set energy 150
  set color-type (violet - 3)
  set color color-type
  set mass (10)  ; atomic masses of oxygen atoms

  set speed speed-from-energy
  set last-collision nobody
  set absorbed? false
  set large? is-large
  set swept? false
end 


; Place particles at random, but they must not be placed on top of wall atoms.
; This procedure takes into account the fact that wall molecules could have two possible arrangements,
; i.e. high-surface area ot low-surface area.

to random-position ;; particles procedure
  let open-patches nobody
  let open-patch nobody
  set open-patches patches with [not any? turtles-here and pxcor != max-pxcor and pxcor != min-pxcor and pycor != min-pycor and pycor != max-pycor]
  set open-patch one-of open-patches

  ; Reuven added the following "if" so that we can get through setup without a runtime error.
  if open-patch = nobody [
    user-message "No open patches found.  Exiting."
    stop
  ]

  setxy ([ pxcor ] of open-patch) ([ pycor ] of open-patch)
  set heading random 360
  fd random-float .4
end 


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; wall penetration error handling procedure
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; if particles actually end up within the wall

to remove-from-walls
  let this-wall walls-here with [ not hidden? ]

  if count this-wall != 0 [
    let available-patches patches with [ not any? walls-here ]
    let closest-patch nobody
    if (any? available-patches) [
      set closest-patch min-one-of available-patches [ distance myself ]
      set heading towards closest-patch
      setxy ([ pxcor ] of closest-patch)  ([ pycor ] of closest-patch)
    ]
  ]
end 


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;GRAPHS;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

to do-plotting
   update-plots
end 


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;REPORTERS;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

to-report speed-from-energy
  report sqrt (2 * energy / mass)
end 

to-report energy-from-speed
  report (mass * speed * speed / 2)
end 

to-report limited-particle-energy
  let limited-energy energy
  if limited-energy > max-particle-energy [ set limited-energy max-particle-energy ]
  if limited-energy < min-particle-energy [ set limited-energy min-particle-energy ]
  report limited-energy
end 


; Copyright 2006 Uri Wilensky.
; See Info tab for full copyright and license.