Binsearch not updating
At one extreme, some computerscience researchers might try to use these concepts to mathematically prove the correctness of a piece of code — perhaps with the proof being an order of magnitude longer than the code.Through the use of a simple but powerful technique, I was able to write compact, clear code in a short time; and be pretty confident, even before I tested it, that it was correct.That last point is important not as some kind of macho posturing, but because it means that the tests, when I run them, are giving a second distinct line of sight on the problem.There are several candidate representations, none of them greatly better or worse than the others: we could keep track of the highest and lowest array indexes that might hold , or the lowest index and the size of the range; or use asymmetric indexes, where we maintain the index to the base of the current range and the index that points past the end.
For this version of the routine, I’m going to arbitrarily choose to represent the range by two variables, if it’s present.
At the other extreme, a seasoned professional developer probably always has at least a fuzzy and informal notion of an invariant in the back of his head whenever he writes a loop.
Binsearch not updating comments 

Numpy/binsearch.at master numpy/numpy GitHub
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Writing correct code, part 1 invariants binary search.
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