Excel to the Rescue
No, I still don’t like Microsoft. But one thing most everyone has in common is they have Excel on their computers.
Last week I talked briefly about the Quality checks. Pain.
During the construction of Version 1.0, we had a large problem. The amortization tables were not producing the correct values. The programmers insisted that the equation was written correctly.
From this point, I had to figure out what happened. Either the equation was faulty or the programmers made a mistake and I had to show them where. Pretty tough considering I didn’t have access to the raw code.
I’ll spare you the long, drawn out process of how I found the problem. Needless to say, a parenthesis was out of place. I notified the programmers, who adjusted it and suddenly everything worked. But finding this error took the better part of a week.
With Version 2.0 coming out, we were adding a bunch more calculations to the application. Checking every single digit would drive me mentally insane. And with calculations depending on calculations you can’t even see, finding a bug would be nearly impossible.
As scary as it sounds, I put Microsoft to work. I created an enormous Excel spreadsheet which housed all the calculations in it. It works the same way as the program, whereas you enter two numbers and it calculates the rest. And because Excel automatically updates, you change one number and all the calculations update. Just like our program.
When I sent along the specification for Version 2.0, I also sent the spreadsheet with the note “Please test all calculations against the attached spreadsheet. You’re required to run three sets of different numbers prior to sending me the application for testing. If the numbers do not match, don’t send me the application until they do. If I find the numbers don’t match during my testing, testing will stop and I’ll send the application back to you with a note to fix it.”
Wouldn’t you know it? The numbers all work like they should. Much nicer.
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