package Random

import Modelica.Math;

constant Real NV_MAGICCONST=4*exp(-0.5)/sqrt(2.0);

type Seed = Integer[3];



function random "input random number generator with external storage of the seed"

  input Seed si "input random seed";

  output Real x "uniform random variate between 0 and 1";

  output Seed so "output random seed";

algorithm

  so[1] := rem((171 * si[1]),30269);

  so[2] := rem((172 * si[2]),30307);

  so[3] := rem((170 * si[3]),30323);

  // zero is a poor Seed, therfore substitute 1;

  if so[1] == 0 then

    so[1] := 1;

  end if;

  if so[2] == 0 then

    so[2] := 1;

  end if;

  if so[3] == 0 then

    so[3] := 1;

  end if;

  x := rem((so[1]/30269.0 +so[2]/30307.0 + so[3]/30323.0),1.0);

end random;



function normalvariate "normally distributed random variable"

  input Real mu "mean value";

  input Real sigma "standard deviation";

  input Seed si "input random seed";

  output Real x "gaussian random variate";

  output Seed so "output random seed";

protected

  Seed s1, s2;

  Real z, zz, u1, u2;

algorithm

  s1 := si;

  u2 := 1;

  while true loop

    (u1,s2) := random(s1);

    (u2,s1) := random(s2);

    z := NV_MAGICCONST*(u1-0.5)/u2;

    zz := z*z/4.0;

    if zz <= (- Math.log(u2)) then

      break;

    end if;

  end while;

  x := mu + z*sigma;

  so := s1;

end normalvariate;



connector discreteConnector

   discrete Boolean dcon;

end discreteConnector;



end Random;

model CustomerGeneration

  Random.discreteConnector dOutput;

  parameter Real mean = 0;

  parameter Real stDeviation = 1;



  discrete Real normalDelta;

  discrete Real nextCustomerArrivalTime(start=0);

  discrete Random.Seed randomSeed(start={23,87,187});



equation

  when pre(nextCustomerArrivalTime)<=time then

    (normalDelta,randomSeed)=Random.normalvariate(mean,stDeviation,pre(randomSeed));

     nextCustomerArrivalTime = pre(nextCustomerArrivalTime) + abs(normalDelta);

   end when;



   dOutput.dcon=if nextCustomerArrivalTime<>pre(nextCustomerArrivalTime) then true

   else  false;

end CustomerGeneration;

simulate( CustomerGeneration, stopTime=10 )

record SimulationResult

    resultFile = "",

    simulationOptions = "startTime = 0.0, stopTime = 10.0, numberOfIntervals = 500, tolerance = 1e-06, method = 'dassl', fileNamePrefix = 'CustomerGeneration', storeInTemp = false, noClean = false, options = '', outputFormat = 'plt'",

    messages = "Simulation failed for model: CustomerGeneration

[<interactive>:44:5-46:11:writable] Error: Class Math.log not found in scope Random.normalvariate (looking for a function or record).

Error: Error occured while flattening model CustomerGeneration

",

    timeFrontend = 0.0,

    timeBackend = 0.0,

    timeSimCode = 0.0,

    timeTemplates = 0.0,

    timeCompile = 0.0,

    timeSimulation = 0.0,

    timeTotal = 0.0

end SimulationResult;