Modification of CombiTable1Ds Modelica model in order to have a piecewise constant function adapted to meteorological data files

Hypothesis and equations

Constant piecewise interpolation in one dimension of a table. Via parameter columns it can be defined how many columns of the table are interpolated. If, e.g., icol={2,4}, it is assumed that one input and 2 output signals are present and that the first output interpolates via column 2 and the second output interpolates via column 4 of the table matrix.



Derived from the Modelica.Blocks.Tables.CombiTable1Ds model .

Instructions for use

The grid points and function values are stored in a matrix "table[i,j]", where the first column "table[:,1]" contains the grid points and the other columns contain the data to be interpolated. Example:

   table = [0,  0;
            1,  1;
            2,  4;
            4, 16]
   If, e.g., the input u = 1.0, the output y =  1.0,
       e.g., the input u = 1.5, the output y =  2.5,
       e.g., the input u = 2.0, the output y =  4.0,
       e.g., the input u =-1.0, the output y = -1.0 (i.e., extrapolation).

The table matrix can be defined in the following ways:

  1. Explicitly supplied as parameter matrix "table", and the other parameters have the following values:
  2.    tableName is "NoName" or has only blanks,
       fileName  is "NoName" or has only blanks.
  3. Read from a file "fileName" where the matrix is stored as "tableName". Both ASCII and MAT-file format is possible. (The ASCII format is described below). The MAT-file format comes in four different versions: v4, v6, v7 and v7.3. The library supports at least v4, v6 and v7 whereas v7.3 is optional. It is most convenient to generate the MAT-file from FreeMat or MATLAB® by command
  4.    save tables.mat tab1 tab2 tab3

    or Scilab by command

       savematfile tables.mat tab1 tab2 tab3

    when the three tables tab1, tab2, tab3 should be used from the model.

    Note, a fileName can be defined as URI by using the helper function loadResource.

  5. Statically stored in function "usertab" in file "usertab.c". The matrix is identified by "tableName". Parameter fileName = "NoName" or has only blanks. Row-wise storage is always to be preferred as otherwise the table is reallocated and transposed. See the Tables package documentation for more details.

When the constant "NO_FILE_SYSTEM" is defined, all file I/O related parts of the source code are removed by the C-preprocessor, such that no access to files takes place.

If tables are read from an ASCII-file, the file needs to have the following structure ("-----" is not part of the file content):

double tab1(5,2)   # comment line
  0   0
  1   1
  2   4
  3   9
  4  16
double tab2(5,2)   # another comment line
  0   0
  2   2
  4   8
  6  18
  8  32

Note, that the first two characters in the file need to be "#1" (a line comment defining the version number of the file format). Afterwards, the corresponding matrix has to be declared with type (= "double" or "float"), name and actual dimensions. Finally, in successive rows of the file, the elements of the matrix have to be given. The elements have to be provided as a sequence of numbers in row-wise order (therefore a matrix row can span several lines in the file and need not start at the beginning of a line). Numbers have to be given according to C syntax (such as 2.3, -2, +2.e4). Number separators are spaces, tab ( ), comma (,), or semicolon (;). Several matrices may be defined one after another. Line comments start with the hash symbol (#) and can appear everywhere. Other characters, like trailing non comments, are not allowed in the file.

MATLAB is a registered trademark of The MathWorks, Inc.

Known limits / Use precautions



Validated model

Licensed by EDF under a 3-clause BSD-license
Copyright © EDF 2009 - 2023
BuildSysPro version 3.6.0
Author : Hassan BOUIA, Amy LINDSAY, EDF (2014)


12/2014 H. Bouia, A. Lindsay : modification du modèle CombiTable1Ds de Modelica afin que la fonction en escaliers corresponde bien à ce qu'on attend en sortie d'un fichier météo

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