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+TODO
+====
+
+* Get rid of all global variables.
+
+* Break main() into smaller chunks; operations that are timed should become independent functions.
+
+* Dynamically allocate the big arrays.
+
+* Create a key-value config file reader to replace the external parameter files.
+
+* Remove all ifdef blocks, options should be selected in the config file.
+
+* Optional HDF5 output.
+
+* In the config file let choose number of digits for ASCII output and 32 or 64-bit floats for HDF5.