if-expression in equation section

[dieter]

Hi,

I try to restrict a variable (inPort.flowrate) to positive values:

equation
  ...
  qt = b*s *  dp*s^2 / (12*m*l);
  q = e0*V*n;
  qq = q - qt;
  inPort.flowrate = if q > qt then qq else 0.;

the values of qt, q, qq seem to be right but the values of
inPort.flowrate are NOT equal to q - qt (but some other very small
values).  Where am I wrong?

Thanks
--
    Best wishes

    H. Dieter Wilhelm
    Darmstadt, Germany