Environment variables

These change what Exudyn does before a script says anything, which is what makes them worth knowing when a run behaves differently than it reads:

variable	what it does
EXUDYN_NO_USER_SETTINGS	anything but empty or 0 ignores ~/.exudyn/config.json completely, so that a run starts from the defaults. runTestSuite.py, runTestExamples.py, runPerformanceTests.py and pytest set it for themselves, so a stored setting can never move a test result
EXUDYN_CONFIG_FILE	names a different settings file, for a second configuration or for a test
EXUDYN_OUTPUTDIRECTORY	the initial value of exudyn.config.outputDirectory: every solution and sensor file a model writes goes there, which is how a model is run without writing into the working directory
EXUDYN_SUPPRESS_UI_WINDOW_OPEN	switches on all of exudyn.special.userInterface: no renderer, no solution viewer, no plot window and no dialog, and matplotlib is switched to its non-interactive backend. Meant for automated runs, where a window that waits for a human stops everything
EXUDYN_MODULE	fast loads exudynCPPfast - no range checks, AVX2 - instead of the regular module; it belongs to release testing, because without range checks a wrong index is undefined behaviour instead of an exception
EXUDYN_IMPORT_VERBOSE	1 prints which compiled module was tried and what came of it, which is the whole answer to it imports the wrong one

Setting one for every run in Spyder: Spyder starts its consoles itself, so a variable is set where a console starts. In Tools > Preferences > IPython console > Startup, under Run code, the lines

import os; os.environ['EXUDYN_OUTPUTDIRECTORY'] = 'solution'

make every run of a restarted console write its output into solution/ beside the script it runs - with the working directory set to the directory of the file being executed, which is Spyder’s default. A script that writes to solution/... itself then writes to solution/solution/.... Outside Spyder, setx EXUDYN_OUTPUTDIRECTORY solution sets the variable for every program the user starts afterwards.

EXUDYN_NO_USER_SETTINGS=1 is also what makes a problem reproducible on a machine that has stored something: run the script with the variable set and the difference is either gone (the stored setting caused it) or still there (it did not).