.Buildings.Fluid.Examples.Performance.Example5

Information

This example illustrates the impact of Modelica code formulations on the C-code.

Compare the C-code in dsmodel.c when setting the parameter efficient to true or false and when adding annotation(Evaluate=true) to the parameter efficient.

This produces:

Efficient = false and Evaluate = false

helpvar[0] = sin(Time);
F_[0] = helpvar[0]*(IF DP_[0] THEN W_[0] ELSE DP_[1]+DP_[2]+DP_[3]);

Efficient = false and Evaluate = true

helpvar[0] = sin(Time);
F_[0] = helpvar[0]*(DP_[0]+DP_[1]+DP_[2]);

Efficient = true and Evaluate = true

helpvar[0] = sin(Time);
F_[0] = helpvar[0]*W_[1];

The last option requires much less operations to be performed and is therefore more efficient.

See Jorissen et al. (2015) for a discussion.

References

• Filip Jorissen, Michael Wetter and Lieve Helsen.
  Simulation speed analysis and improvements of Modelica models for building energy simulation.
  Submitted: 11th Modelica Conference. Paris, France. Sep. 2015.

Revisions

• March 6, 2023, by Michael Wetter:
  Added a constant in order for unit check to pass.
  See #1711 for a discussion.
• July 14, 2015, by Michael Wetter:
  Revised documentation.
• April 17, 2015, by Filip Jorissen:
  First implementation.