modelica
CombiTimeTable does not have the ability to find max/min ordinate (y) value
Tables in ModelicaStandardTables.c (in particular the source block CombiTimeTable) can find the maximum and minimum abscissa (x-value, or 'time'), but cannot find the maximum and minimum ordinate (y-value, or 'data'). I would like to ask if there is any limitation or consideration keeping such a functionality from being implemented; there can be situations where knowing the min/max values inside an input table is useful before the timestepping has started.
I managed to make a copy of Modelica.Blocks.Sources.CombiTimeTable, add another parameter inside and call an external C function maximimValue as shown below.
external_C_code_additon.c:
/* redefine calls locally */
#define TABLE_ROW0(j) table[j]
#define TABLE_COL0(i) table[(i)*nCol]
/* make some local definitions just as in the original, for the function to work */
typedef size_t Interval[2];
typedef struct CombiTimeTable {
char* key; /* Key consisting of concatenated names of file and table */
double* table; /* Table values */
size_t nRow; /* Number of rows of table */
} CombiTimeTable;
/* function */
double maximumValue(void* _tableID) {
double yMax = 0.;
CombiTimeTable* tableID = (CombiTimeTable*)_tableID;
if (NULL != tableID && NULL != tableID->table) {
const double* table = tableID->table;
const size_t nRow = tableID->nRow;
yMax = TABLE_ROW0(0);
int i;
for (i = 1; i < nRow; i++) {
if (TABLE_ROW0(i) > yMax) {
yMax = TABLE_ROW0(i);
}
}
}
return yMax;
}
This will probably work for my project. I wasn't able to edit the ModelicaStandardTables .c and .h files as it appears they are precompiled in OpenModelica - no changes seemed to be reflected in my test models.
Unless there are objections, I may fork this repo and produce a pull request. (I am not familiar with development for MSL so it might take a while to be able to test the functionality properly). This might be same for all other MSL table blocks but I have not explored them.
If you use spline-interpolation it may be more complicated as the maximum might be between the data-points (at least for some splines, don't know if it is relevant in MSL).
Why do you need this functionality?
I'm looking at figuring out the maximum value in the input table (either a defined peak or a steady-state) as some parameters depend on it. Admittedly I don't need spline interpolation and I see why a min/max would be problematic.
Extrapolation is another issue to consider/disable then.
Going to close this issue as wontfix.
