WOLFRAM SYSTEMMODELER

Tables

Library of blocks to interpolate in one and two-dimensional tables

Package Contents

CombiTable1D

Table look-up in one dimension (matrix/file) with n inputs and n outputs

CombiTable1Ds

Table look-up in one dimension (matrix/file) with one input and n outputs

CombiTable2D

Table look-up in two dimensions (matrix/file)

CombiTable2Dv

Table look-up in two dimensions (matrix/file) with vector inputs and vector output of size n

Internal

Internal external object definitions for table functions that should not be directly utilized by the user

Information

This information is part of the Modelica Standard Library maintained by the Modelica Association.

This package contains blocks for one- and two-dimensional interpolation in tables.

Special interest topic: Statically stored tables for real-time simulation targets

Especially for use on real-time platform targets (e.g., HIL-simulators) with no file system, it is possible to statically store tables using a function "usertab" in a file conventionally named "usertab.c". This can be more efficient than providing the tables as Modelica parameter arrays.

This is achieved by providing the tables in a specific structure as C-code and compiling that C-code together with the rest of the simulation model into a binary that can be executed on the target platform. The "Resources/Data/Tables/" subdirectory of the MSL installation directory contains the files "usertab.c" and "usertab.h" that can be used as a template for own developments. While "usertab.c" would be typically used unmodified, the "usertab.h" needs to adapted for the own needs.

In order to work it is necessary that the compiler pulls in the "usertab.c" file. Different Modelica tools might provide different mechanisms to do so. Please consult the respective documentation/support for your Modelica tool.

A possible (though a bit "hackish") Modelica standard conformant approach is to pull in the required files by utilizing a "dummy"-function that uses the Modelica external function interface to pull in the required "usertab.c". An example how this can be done is given below.

model Test25_usertab "Test utilizing the usertab.c interface"
  extends Modelica.Icons.Example;
public
  Modelica.Blocks.Sources.RealExpression realExpression(y=getUsertab(t_new.y))
    annotation (Placement(transformation(extent={{-40,-34},{-10,-14}})));
  Modelica.Blocks.Tables.CombiTable1D t_new(tableOnFile=true, tableName="TestTable_1D_a")
    annotation (Placement(transformation(extent={{-40,0},{-20,20}})));
  Modelica.Blocks.Sources.Clock clock
    annotation (Placement(transformation(extent={{-80,0},{-60,20}})));
protected
  encapsulated function getUsertab
    input Real dummy_u[:];
    output Real dummy_y;
    external "C" dummy_y=  mydummyfunc(dummy_u);
    annotation(IncludeDirectory="modelica://Modelica/Resources/Data/Tables",
           Include = "#include "usertab.c"
double mydummyfunc(double* dummy_in) {
   return 0;
}
");
  end getUsertab;
equation
  connect(clock.y,t_new. u[1]) annotation (Line(
      points={{-59,10},{-42,10}}, color={0,0,127}));
  annotation (experiment(StartTime=0, StopTime=5), uses(Modelica(version="3.2.3")));
end Test25_usertab;

Wolfram Language

In[1]:=
SystemModel["Modelica.Blocks.Tables"]
Out[1]:=