🚀 go-pugleaf

In article <1992Apr15.233338.3786@yrloc.ipsa.reuter.COM> rbe@yrloc.ipsa.reuter.COM (Robert Bernecky) writes:
|  Morgan Stanley Bank in NYC runs a foreign exchange trading system 
|  under SHARP APL. On Black Monday a few years ago, trade volumes and
|  $$ were so high that most systems either died (overflow) or got
|  drastically behind, giving their traders Very Bad Data, causing said
|  traders to trade themselves (and their firms) much further into the
|  red. Morgan's APL-based system not only didn't die (integers went to
|  real instead of getting integer overflow death), but the system didn't
|  fall behind, AND Morgan made a profit that day! 

This is a practise that will LITERALLY send you to prison in most
countries. Financial calculations MUST be performed to 100ths of a
cent (or whatever local law prescribes) and must NOT be rounded except
as permitted by law. I am literally shocked that you would consider
this a good solution to a practical problem.

|  The specification of "I'll make this integer because it'll run faster, 
|  and take less space, and I KNOW IT CAN't possibly overflow" school
|  was totally unprepared for the volumes traded that day. 
|  It simply was not thought possible. 

No, you make it an integer so that it will trap if it loses precision.
(-: Then again, maybe this is a business in which it's considered to
be better to be rich and in prison? :-).

|Where I come from, we get "index error". We also signal "index error"
|on things like indexing with negatives, or with numbers > shape of array
|axis, unlike C and Fortran. But that's only because we're silly types
|who care more about correct results than speed.

An interesting juxtaposition, since if you wanted correct results
rather than speed you'd use bignums and constructive reals.
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stephen p spackman         Center for Information and Language Studies
stephen@estragon.uchicago.edu                    University of Chicago
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