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Is COBOL Holding you Hostage with Math?

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

An Anonymous Coward writes:

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: 2) by FatPhil on Wednesday September 18 2019, @08:19AM (1 child)

    by FatPhil (863) <{pc-soylent} {at} {asdf.fi}> on Wednesday September 18 2019, @08:19AM (#895536) Homepage
    Never knew about the MS centi-cents - interesting. That has the side effect of still forcing the programmer to do with the centi-cents they don't want to propagate to the outside world (invoice/etc.). I don't like the implication that every single step of a financial calculation will be performed in this type, because the errors would accumulate at a terifying rate compared with how quickly they would if you were performing the calculations in FP, unless everything you are dealing with was multi-billion. I fear this might be a half-baked idea. Inside the black box, always use the best tool for the job. There really needs to be 2 currency types - currency-for-userspace and currency-for-calculations - where the user should never see or use the latter.
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  • (Score: 2) by DannyB on Wednesday September 18 2019, @01:58PM

    by DannyB (5839) Subscriber Badge on Wednesday September 18 2019, @01:58PM (#895640) Journal

    Microsoft has had its currency type since at least the 1990's. It is in all their languages, as far as I know, but started in VB, I think. At the time it probably seemed like a good idea. And it probably stopped many programmers from using floating point instead.

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