w09-tsk1-basic-example-debug

Basic Example and Debug: Putting everything together

Objective

The overall objective of this task is to implement a basic example, which combines the various parts that we have been implementing over the past weeks. This basic example will be able to solve a problem of our choice. Furthermore, you will likely have to find bugs.

Implementation

0. load appropriate modules by performing the following command in your terminal: source tehpc/tools/tehpc_load_modules.sh.

1. Consider the file named basic_example.cpp which is provided in the tehpc/examples/ directory.

2. Modify tehpc/examples/CMakeLists.txt such that it will compile the basic_example.

3. Compile your code, use the following steps:

   a. go into tehpc/build/

   b. type: either cmake -DCMAKE_BUILD_TYPE:STRING=Debug -DTEHPC_EXAMPLES:STRING=ON .. or ccmake .. to configure (you only have to do this the very first time).

   c. type: make (do this whenever you want to recompile).

4. Check that all the tests pass:

   a. go into tehpc/build/tests/

   b. to run all tests at once, type: make test

5. Likely, you will have at least one test failing. Correct the code such that all tests pass.

   a. at this point, your model does not have any solver. Make sure that the Model constructor calls the appropriate method (of Model) to register a solver based on information received in the input file.

   b. despite calling the register method, there is still no solver initiated. To solve this, have a look at the function init_solver(...) in nonlinear_solver.cpp and complete it following indications provided in the file.

6. Implement the basic_example. It should do the following things:

   a. complete the basic_example.cpp file following the indications in the file. You will have to call various methods of the Model class. Some are new and provided with the preparation of the task. You can use the Doxygen-produced code catalogue to find appropriate methods.

7. Correct all compilation errors.

8. If the code compiles without errors, run the example basic_example:

   a. go into tehpc/build/examples/

   b. type: ./basic_example (this will run it with default input file)

   c. one can run the example for other input files with type: ./basic_example hancock . with the relevant arguments. You can run it for the 2dtruss and the hancock example, for both of which the input files are provided already in tehpc.

9. Use the following different strategies to find the bug (or if you already found it, improve the code)

   a. go through the code step-wise using gdb following the instructions from the demonstration (see other issue)

   b. you can decide to print more information to the screen. However, you do not want to permanently print information that the user does not need. For this, we included an option.

   i. Go into ccmake . and put TEHPC_VERBOSE ON (use the crtl-shift-p > CMake: Edit CMake Cache (UI) and select the option TEHPC_VERBOSE ON

   ii. recompile

   iii. wherever in the code, you would like to print information, you can add #ifdef TEHPC_VERBOSE then std::cout << ... << std::endl;, and end with #endif. (just for your information, this was possible because of option in tehpc/tehpc_config.hpp.in file.) When you want to run clean simulations, you simply put the TEHPC_VERBOSE option in cmake on OFF.

   iv. Add such verbose printing at appropriate places in the important functions for this debugging case.

10. At some points, it might be good to check values to satisfy known conditions. You can use the throw command to throw a relevant error, if the conditions are not satisfied. You can then use the try functionality and catch the error to deal with it appropriately.

11. Once your code runs through and converges, check if the results are reasonable (use the analysis.ipynb notebook to do so).

12. run valgrind to check for memory leakage: valgrind --leak-check=full ./basic_example. Correct memory leakage if you encounter problems.

13. In previous tasks over the past weeks, we added print statements to various functions in various classes (e.g., model, solvers, ...). Many of them are only needed when debugging. Please place them now between #ifdef TEHPC_VERBOSE and #endif statements.

14. Make sure that your code is well structured and commented.