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posted by martyb on Monday September 16 2019, @01:48PM   Printer-friendly
from the COBOL-is-often-fractionally-better dept.

https://medium.com/@bellmar/is-cobol-holding-you-hostage-with-math-5498c0eb428b

Face it: nobody likes fractions, not even computers.

When we talk about COBOL the first question on everyone's mind is always Why are we still using it in so many critical places? Banks are still running COBOL, close to 7% of the GDP is dependent on COBOL in the form of payments from the Centers for Medicare & Medicaid Services, The IRS famously still uses COBOL, airlines still use COBOL (Adam Fletcher dropped my favorite fun fact on this topic in his Systems We Love talk: the reservation number on your ticket used to be just a pointer), lots of critical infrastructure both in the private and public sector still runs on COBOL.

Why?

The traditional answer is deeply cynical. Organizations are lazy, incompetent, stupid. They are cheap: unwilling to invest the money needed upfront to rewrite the whole system in something modern. Overall we assume that the reason so much of civil society runs on COBOL is a combination of inertia and shortsightedness. And certainly there is a little truth there. Rewriting a mass of spaghetti code is no small task. It is expensive. It is difficult. And if the existing software seems to be working fine there might be little incentive to invest in the project.

But back when I was working with the IRS the old COBOL developers used to tell me: "We tried to rewrite the code in Java and Java couldn't do the calculations right."

[Ed note: The referenced article is extremely readable and clearly explains the differences between floating-point and fixed-point math, as well as providing an example and explanation that clearly shows the tradeoffs.]


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  • (Score: 3, Informative) by DannyB on Monday September 16 2019, @05:59PM

    by DannyB (5839) Subscriber Badge on Monday September 16 2019, @05:59PM (#894730) Journal

    It is powers of 10 true. But it is also true that currencies are ALWAYS integers. Never approximations like floating point.

    Once you recognize it is integers, you can use integer types for much greater efficiency. Integer arithmetic is always EXACT. Even division has an exact quotient and remainder. EXACT. No fuzzyness, ambiguity or imprecision. All currency values (within range) are exactly representable as integer. Conversion to and from Base 10 for printing and parsing is also EXACT. So for Five Dollars you would use an integer of 500.

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    People today are educated enough to repeat what they are taught but not to question what they are taught.
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