id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
2279	Initialisation problem in equation section when using random generation function	e.ypma@…	Lennart Ochel	"When I try to simulate the model 'test_MR' it results in the first time step in a huge output (~10^21). 
After that, it never recovers. 

{{{
// within Random;

record SEEDINFO
  Real s1;
  Real s2;
  Real s3;
end SEEDINFO;

function MathRandom

  input SEEDINFO si;
  input Real tim;
  output Real x(start=0.0);
  output SEEDINFO so;

protected
  Real a=0.0,b=0.0,c=0.0; 
  Real s1=0.0, s2=0.0, s3=0.0; 
algorithm
  
  s1 := si.s1;
  s2 := si.s2;
  s3 := si.s3;
     
  a := mod(tim-11,tim+13);
  a := exp(a);
  a := rem(171*s1*a,30269);
  a := abs(a);
   
  b := mod(tim-5,tim+7); 
  b := exp(b);
  b := rem(172*s2*b,30307);
  b := abs(b);
  
  c := mod(tim-23,tim+76);
  c := exp(c);
  c := rem(170*s3*c,30323);  
  c := abs(c);

  if a < 1e-4 then
    a := 1.0;
  end if;
  if b < 1e-4 then
    b := 1.0;
  end if;
  if c < 1e-4 then
    c := 1.0;
  end if;
  x := rem((a/30269.0+b/30307.0+c/30323.0),1.0);
  
  so.s1 := a;
  so.s2 := b;
  so.s3 := c;
 
end MathRandom;

//-----------------------------------------------------------
//- For direct use in OMShell:
//- 	- Initialise ALL variables
//- 	- Call repeatedly: (r, s1,s2,s3) := MR(s1,s2,s3,t);
//-   Result: random r.
function MR
  input Real si1,si2,si3;
  input Real t;
  output Real x;
  output Real so1,so2,so3;
  protected
  SEEDINFO s;
algorithm
  s.s1:=si1;
  s.s2:=si2;
  s.s3:=si3;
  (x,s):=MathRandom(s,t);
  so1 := s.s1;
  so2 := s.s2;
  so3 := s.s3;
end MR;

//-----------------------------------------------------------

model test_MathRandom
  output Real y(start=0.0);
  parameter Real dtSample = 0.1;

protected
  SEEDINFO s(s1(start=1.0), s2(start=2.0), s3(start=3.0));
  Real x(start=0.0);
  Real s1, s2, s3;
algorithm
  (x,s):=MathRandom(s,time/10.0);
  s1 := s.s1;
  s2 := s.s2;
  s3 := s.s3;
equation
  when sample(0.0, dtSample) then
    y = x;
end when;
end test_MathRandom;

//-----------------------------------------------------------

model test_MR
  output Real y(start=0.0);
  parameter Real dtSample = 0.1;

protected
  Real s1(start=1.0), s2(start=2.0), s3(start=3.0);
  Real x(start=0.0);
algorithm
  (x,s1,s2,s3) := MR(s1,s2,s3,time/10.0);
equation
  when sample(0.0, dtSample) then
    y = x;
end when;
end test_MR;
}}}


However, when I call the function MR directly in the notebook 
repeatedly) then I get the expected output (a changing random number).

The same problem occurs when trying to run the Kalman model in DrControl (it is based on the same noise generation function).

Using the MDT debugger it seems to go wrong when calculating the 
remainder from c but only when calling MR in test_MR, not when calling it directly because then it gives correct results. The other thing is that in MDT the values for s1, s2, s3 never change.
"	defect	closed	high	1.9.0	Backend	trunk	fixed	random number generation