Issue with delay() in the NF

[Francesco Casella]

Please run this test model with the NF

model TestDelay
  Real x(start = 0, fixed = true);
  Real y;
equation
  der(x) = 1 - x;
  y = delay(x,1);
  annotation(experiment(StopTime=5));
end TestDelay;

The result is y = 0, which is wrong.

The model flattened with the old FE gives

  y = delay(x, 1.0, 1.0);

while the new FE returns

  y = delay(x, 1.0);

Apparently the back-end expects that delayMax is computed by the NF in the case it is not supplied and delayTime is a parameter expression.

Please provide this also with the NF.

[Per Östlund]

Should be fixed in 3729dd6. I just changed the definition in ModelicaBuiltin so that delay(expr, delayTime) = delay(expr, delayTime, delayTime).

[Francesco Casella]

Indeed it works, now ScalableTestSuite.Electrical.TransmissionLine.Verification.TransmissionLineCheck passes verification, see ​report.

As a final remark, when delay(expr,delayTime) is used, you should check that delayTime is a constant or a parameter expression, otherwise you should issue an error, since the backend (following the specification) expects delayMax to be a parameter expression.

[Per Östlund]

Replying to casella:

As a final remark, when delay(expr,delayTime) is used, you should check that delayTime is a constant or a parameter expression, otherwise you should issue an error, since the backend (following the specification) expects delayMax to be a parameter expression.

This already seems to be the case, due to delayTime being declared as parameter in the definition of delay with two arguments. The error message that's generated could be better, but at least it works.

[Francesco Casella]

Ok, very good!