.BuildingSystems.Utilities.Math.Functions.interpolate

Information

This function returns the value on a cubic hermite spline through the given support points and provided spline derivatives at these points. The spline derivatives at the support points can be computed using BuildingSystems.Utilities.Math.Functions.splineDerivatives. The support points must be monotonically increasing. Outside the provided support points, the function returns a linear extrapolation with the same slope as the cubic spline has at the respective support point.

A similar model is also used in the CONTAM software (Dols and Walton, 2015).

This function is used in BuildingSystems.Airflow.Multizone.Table_m_flow and BuildingSystems.Airflow.Multizone.Table_V_flow

References

• W. S. Dols and B. J. Polidoro,2015. CONTAM User Guide and Program Documentation Version 3.2, National Institute of Standards and Technology, NIST TN 1887, Sep. 2015. doi: 10.6028/NIST.TN.1887.

Interface

function interpolate
  extends Modelica.Icons.Function;
  input Real u "Independent variable";
  input Real[:] xd "x-axis support points";
  input Real[size(xd, 1)] yd "y-axis support points";
  input Real[size(xd, 1)] d "Derivatives at the support points";
  output Real z "Dependent variable with monotone interpolation";
end interpolate;

Revisions

• February 29, 2024, by Hongxiang Fu:
  Moved to BuildingSystems.Utilities.Math.Functions from BuildingSystems.Airflow.Multizone.BaseClasses.
  This is for IBPSA, #1844.
• February 26, 2024, by Hongxiang Fu:
  Correct implementation to make it smooth.
  This is for IBPSA, #1840.
• February 2, 2022, by Michael Wetter:
  Revised implementation.
  This is for IBPSA, #1436.
• Apr 6, 2021, by Klaas De Jonge:
  First Implementation.