But
===

Extract a numeric value or an attribute from a function for comparison to a reference value. The function is a data structure such as a function or table.

This procedure then writes a conventional message "OK" (if it is good) or "NOOK" (if not).

It does not stop the execution if the test is not verified; this allows it to be used either systematically for validation tests, or to extract and print a value of a function or a table for a particular value of a parameter.

This command is used mainly by test cases to validate the non-regression of the results.