| Author | Message | ||
     Lichun Zhu (lzhu) New member Username: lzhu Post Number: 1 Registered: 11-2003 |
hi, I am new to flexpde. One thing I want to know is that can we implement external functions calls like function calls in C language (either in C or flexPDE script)? This way we can easily call that function in the main FlexPde script. | ||
| Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 61 Registered: 06-2003 |
FlexPDE does not have facilities for linking to external C code. The FlexPDE scripting language contains extensive facilities for defining cascaded dependencies. Just define your dependency in the DEFINITIONS section, and FlexPDE will figure out how to use it. Many of our examples use such definitions. See for example "Samples | steady_state | chemistry | reaction.pde". Or you can use the TABLE facility to encode the results of complex external computations. Table coordinates are arbitrary, so you can tabulate vs a computed quantity. | ||
| Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 62 Registered: 06-2003 |
You can also use what we call "Parameterized definitions" (equivalent to "function definitions"). See the Help section "Problem Descriptor Reference | Sections | Definitions | Parameterized Definitions" and the example "Samples | Misc | Funcdef.pde". [Note that these definitions are text-replacement functions, not runtime calls.] | ||
| Lichun Zhu (lzhu) New member Username: lzhu Post Number: 2 Registered: 11-2003 |
Hi, Robert: Thanks for your reply. I am doing a permafrost thermal modeling project. For that, I need quite complex boundary condition, that boundary condition will be the output of another ecosystem model. But the ecosystem model will also need the Temperature (it will be the field variable in the PDE). Then this two models need dynamic interaction in each step. The ecosystem model is already in C. If FlexPde have the capability to link external functions (just the same as your internal functions such as sin(t)), It will be a great improvement for your software, it will provide great flexibility to user. Do you have any plan to add this kind of capability? Thanks. | ||
| Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 63 Registered: 06-2003 |
Linking to external functions raises serious difficulties in defining what part of the FlexPDE environment needs to be passed to the external function, and how to specify that export. We do not at present have plans to implement this facility. You can export data tables as a result of the FlexPDE computation, and you can read in tables from an external source. But this cannot be done on a timestep-by-timestep basis. The best I can offer is that you try to condense the results of your external computation into a 1- 2- or 3-dimensional table in which FlexPDE can look up the BC behavior. | ||
| Lichun Zhu (lzhu) Junior Member Username: lzhu Post Number: 3 Registered: 11-2003 |
Hi, Robert: I think theoretically, this can be fairly straight forward. For example: For each step: TIME From StartTime To EndTime By TimeInc Call BoundaryFunc(PreviousStepTemperatureArray, return_value_of_current_step_boundary_TemperatureArray) Internally, you need to call this function at each step. Any comments? |