id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
4740	"""if noEvent()"" won't protect sqrt from being called"	Henning Kiel	Lennart Ochel	"{{{#!modelica
model behaelter
  parameter Real A = 5;
  parameter Real V0 = 0;
  parameter Real g = 9.81;
  parameter Real k = 0.1;
  Real h, fout, fin, v, V;
initial equation
  V=V0;
equation
  der(V) = -fout+fin;
  if noEvent(V >= 0)then
    A*h = V;
    v = sqrt(2*g*h);
    fout = k*v;
  else
    fout = 0;
    h = 0;
    v = 0;
  end if;
end behaelter;
}}}
{{{#!modelica
model wasserkette
  behaelter b1(V0 = 1);
equation
  if noEvent(time < 10)then
    b1.fin = 0.25;
  else
    b1.fin = 0;
  end if;
end wasserkette;
}}}

When I {{{simulate(wasserkette,stopTime=20)}}} I get the following output:
{{{
record SimulationResult
    resultFile = ""wasserkette_res.mat"",
    messages = ""assert            | debug   | division leads to inf or nan at time 0, (a=6.93672) / (b=0), where divisor b is: sqrt(b1.g * b1.h)
LOG_SUCCESS       | info    | The initialization finished successfully without homotopy method.
assert            | warning | The following assertion has been violated at time 10.560000
assert            | debug   | Model error: Argument of sqrt(b1.g * b1.h) was -0.186758 should be >= 0
assert            | warning | The following assertion has been violated at time 10.560000
assert            | debug   | Model error: Argument of sqrt(b1.g * b1.h) was -0.154058 should be >= 0
assert            | debug   | division leads to inf or nan at time 21.9614, (a=0) / (b=0), where divisor b is: sqrt(b1.g * b1.h)
assert            | debug   | division leads to inf or nan at time 20.1835, (a=0) / (b=0), where divisor b is: sqrt(b1.g * b1.h)
LOG_SUCCESS       | info    | The simulation finished successfully.
""
end SimulationResult;

""Warning: Iteration variables with default zero start attribute in equation system w/o analytic Jacobian:
         b1.v:VARIABLE()  type: Real 
         b1.h:VARIABLE()  type: Real 
         b1.fout:VARIABLE()  type: Real
""
}}}

Moving either {{{A*H=V}}} or {{{fout=k*v}}} out of the if expression (and removing the corresponding equation from else branch) leads to successfull simulation."	defect	new	high	Future	Backend				Willi Braun Lennart Ochel