Competitive Market

globals [PriceEquilibrium QuantityEquilibrium QuantityIntercept
  Prices
  RandomMeanQuantity RandomMeanPrice]

to Setup
  ;; (for this model to work with NetLogo's new plotting features,
  ;; __clear-all-and-reset-ticks should be replaced with clear-all at
  ;; the beginning of your setup procedure and reset-ticks at the end
  ;; of the procedure.)
  __clear-all-and-reset-ticks
  set QuantityIntercept  DemandPriceIntercept / abs DemandSlope
  PlotSupplyAndDemandCurves
  
  set QuantityEquilibrium  DemandPriceIntercept / (SupplySlope - DemandSlope)
  set PriceEquilibrium SupplySlope * QuantityEquilibrium
  
  PlotSupplyAndDemandResolutions
  
  set Prices []
end 

to PlotSupplyAndDemandCurves
  set-current-plot "Supply and Demand Curves"
  set-current-plot-pen "Demand"   
  ;print (word "QuantityIntercept = " QuantityIntercept)
  plot-pen-up
  plotxy 0 DemandPriceIntercept
  plot-pen-down
  plotxy QuantityIntercept 0
  set-current-plot-pen "Supply"
  plot-pen-up
  plotxy 0 0
  plot-pen-down
  plotxy QuantityIntercept SupplySlope * QuantityIntercept 
end 

to PlotSupplyAndDemandResolutions
  set-current-plot "Supply and Demand Resolutions"
  set-current-plot-pen "Demand"
  print (word "QuantityIntercept = " QuantityIntercept)
  plot-pen-up
  plotxy 0 DemandPriceIntercept
  plot-pen-down
  plotxy QuantityIntercept 0
  set-current-plot-pen "Supply"
  plot-pen-up
  plotxy 0 0
  plot-pen-down
  plotxy QuantityIntercept SupplySlope * QuantityIntercept 
  set-current-plot-pen "Average"
  plot-pen-up
  plotxy 0 DemandPriceIntercept / 2.0
  plot-pen-down
  plotxy QuantityIntercept ((DemandPriceIntercept + (DemandSlope + SupplySlope) * QuantityIntercept)) / 2.0
  set-current-plot-pen "Random Mean"
  plot-pen-up
  set RandomMeanQuantity (QuantityEquilibrium / 2)
  plotxy  RandomMeanQuantity 0
  let RandomMeanSupply SupplySlope * RandomMeanQuantity
  let RandomMeanDemand DemandPriceIntercept + DemandSlope * RandomMeanQuantity
  set RandomMeanPrice (RandomMeanSupply + RandomMeanDemand) / 2.0
  plot-pen-down
  plotxy (QuantityEquilibrium / 2) DemandPriceIntercept
end 

to Go
  tick
  let SupplyGuy random-float QuantityTradeMax ; QuantityEquilibrium
  let SupplyReservation SupplyGuy * SupplySlope
  let DemandGuy random-float QuantityTradeMax ; QuantityEquilibrium
  let DemandReservation DemandPriceIntercept + DemandSlope * DemandGuy
  set-current-plot "Prices"
  set-plot-x-range 0 round ( DemandPriceIntercept  - PriceEquilibrium + 5)
  set-plot-y-range 0 100 ;( DemandPriceIntercept  - PriceEquilibrium)
  set-histogram-num-bars 100
  if (SupplyReservation <= DemandReservation)
    [let DaPrice (SupplyReservation + DemandReservation) / 2
     set Prices lput DaPrice Prices        
        set-current-plot-pen "Price"
        set-plot-pen-mode 1
        plot-pen-down
        histogram Prices
      ]
;    [print (word "This should not happen! Quitting.")
;     let bob 0
;     let carol 3 / bob
;    ]
end