Suppose I write an implementation for a function that is usually conceived of as an inverse. For example y = asin(x) [inverse sine].
There are two standard ways to check my implementation. One is simply to compare with a trusted version (for example from mathworks).
The other would be to compute (for a large number of values) abs(sin(asin(x)) - x) where asin is my function [of course, one needs to assume that sin works with sufficient accuracy]. What is the name for the latter testing technique? Would it be called "substitution"?
[The above absolute value is not always close to 0, I realise. But that's a little bit irrelevant to my terminological question. Assume that x is in a quadrant such that the absolute value is theoretically 0].