Implementing else_when (from MathCore)

[krsta]

Elsewhen should be implemented. Eg.g. the model below does not instantiate due to elsewhen statement.

model Square
  Real x(start=-1);
  Real y;
  Real z;
  Real q;
  Real w1,w2;
equation 
  when sample(2.5, 0.5) then
    x=-pre(x);
    q = x+1;
  end when;

  when sample(1.5, 0.5) then
   w1 = 4;
   w2 = 1.4;
  elsewhen sample(2.5, 0.5) then
   w1 = 1.2;
   w2 = 2;
  end when;  



  y=if time < 2.5 then 0 else x;
  z = y;
end Square;

[brugard]

​http://intranet/trac/mathmodelica/ticket/1092

[sjoelund.se]

Works in trunk