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Posts by Cathay Coof
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2020-04-15 at 10:45 PM UTC in Shouldn't there be a LGBTQQIPP2SAA+ safe space on this forum?Bronies deserve the oven.
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2020-04-15 at 10:29 PM UTC in WARIAT FINALLY GETS TOLD HE IS A RETARDI forgot about artstation. The standard of the work there is incredible.
https://www.artstation.com/
This is basically what Wario wishes his portal knight looked like:
https://www.artstation.com/artwork/9eq2GL -
2020-04-15 at 10:23 PM UTC in Learn COBOL!Nope, assembly. Had to go to Archive.org for the actual story, not just the simplified version:
Roundoff Error and the Patriot Missile
https://web.archive.org/web/20090416015820/http://www.mc.edu/campus/users/travis/syllabi/381/patriot.htm
Robert Skeel
The March 13 issue of Science carried an article claiming, on the basis of a report from the General Accounting Office (GAO), that a "minute mathematical error … allowed an Iraqi Scud missile to slip through Patriot missile defenses a year ago and hit U.S. Army barracks in Dhahran, Saudi Arabia, killing 28 servicemen." The article continues with a readable account of what happened.
The article says that the computer doing the tracking calculations had an internal clock whose values were slightly truncated when converted to floating-point arithmetic. The errors were proportional to the time on the clock: 0.0275 seconds after eight hours and 0.3433 seconds after 100 hours. A calculation shows each of these relative errors to be both very nearly 2-20, which is approximately 0.0001%.
The GAO report contains some additional information. The internal clock kept time as an integer value in units of tenths of a second, and the computer's registers were only 24 bits long. This and the consistency in the time lags suggested that the error was caused by a fixed-point 24-bit representation of 0.1 in base 2. The base 2 representation of 0.1 is nonterminating; for the first 23 binary digits after the binary point, the value is 0.1 × (1 - 2-20). The use of 0.1 × (1 - 2-20) in obtaining a floating-point value of time in seconds would cause all times to be reduced by 0.0001%.
This does not really explain the tracking errors, however, because the tracking of a missile should depend not on the absolute clock-time but rather on the time that elapsed between two different radar pulses. And because of the consistency of the errors, this time difference should be in error by only 0.0001%, a truly insignificant amount.
Further inquiries cleared up the mystery. It turns out that the hypothesis concerning the truncated binary representation of 0.1 was essentially correct. A 24-bit representation of 0.1 was used to multiply the clock-time, yielding a result in a pair of 24-bit registers. This was transformed into a 48-bit floating-point number. The software used had been written in assembly language 20 years ago. When Patriot systems were brought into the Gulf conflict, the software was modified (several times) to cope with the high speed of ballistic missiles, for which the system was not originally designed.
At least one of these software modifications was the introduction of a subroutine for converting clock-time more accurately into floating-point. This calculation was needed in about half a dozen places in the program, but the call to the subroutine was not inserted at every point where it was needed. Hence, with a less accurate truncated time of one radar pulse being subtracted from a more accurate time of another radar pulse, the error no longer cancelled.
In the case of the Dhahran Scud, the clock had run up a time of 100 hours, so the calculated elapsed time was too long by 2-20 × 100 hours = 0.3433 seconds, during which time a Scud would be expected to travel more than half a kilometer.
The roundoff error, of course, is not the only problem that has been identified: serious doubts have been expressed about the ability of Patriot missiles to hit Scuds.
Robert Skeel is a professor of computer science at the University of Illinois at Urbana-Champaign.
From SIAM News, July 1992, Volume 25, Number 4, page 11 -
2020-04-15 at 10:04 PM UTC in Learn COBOL!Or maybe it was C or Ada. Can't find shit on specifics.
https://hackaday.com/2015/10/22/an-improvement-to-floating-point-numbers/
OTOH the Ariane 5 failure was Ada.
http://www-users.math.umn.edu/~arnold//disasters/ariane5rep.html -
2020-04-15 at 9:41 PM UTC in This album doesn't show up when you google it - you have to use bing
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2020-04-15 at 9:38 PM UTC in Learn COBOL!
Originally posted by rabbitweed ???
The gulf war ended in 1991. Java was released in 1995.
Nice spot.
It was apparently assembly.
https://www.iro.umontreal.ca/~mignotte/IFT2425/Disasters.htmlhttps://www.iro.umontreal.ca/~mignotte/IFT2425/Disasters.html
https://embeddedgurus.com/barr-code/2014/03/lethal-software-defects-patriot-missile-failure/ -
2020-04-15 at 9:18 PM UTC in You guys call this good gay porn?Honestly, this is what OP's art is tending towards, stylistically.
https://www.pinterest.ie/sarahbecker29/schizophrenia-art/ -
2020-04-15 at 9:16 PM UTC in You guys call this good gay porn?I kinda had myself convinced that that white blob was just a particularly unfortunate puff of smoke or something. A head? Goddam.
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2020-04-15 at 9:04 PM UTC in What is your opinion Jig
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2020-04-15 at 8:50 PM UTC in You guys call this good gay porn?
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2020-04-15 at 8:47 PM UTC in Learn COBOL!
Closing the COBOL Programming Skills Gap
https://ibmsystemsmag.com/IBM-Z/10/2019/closing-cobol-programming-skills-gap
By Phil Teplitzky
10/25/2019
The backbone of today's electronic commerce is COBOL on an IBM Z computing platform. There are 240 billion lines of COBOL in operation, and another 5 billion new lines are added each year. $3 trillion of commercial transactions are processed by COBOL applications each day. COBOL is what business runs on.
Some reports indicate that the 240 billion lines of COBOL code are the second most valuable asset in America, right behind oil. How did COBOL weather 60 years of technological evolution? Because there are classes of information processing that are ideally suited for COBOL on a mainframe. Back-end, high-volume transaction processing must work correctly, securely and fast. If you must process several million transactions in the six-hour overnight batch window, IBM Z COBOL is what you use.
But the community of COBOL programmers is shrinking faster than the open positions they create can be filled. The average age of a COBOL programmer is 58, and roughly 10% are retiring each year.
Emulator for IBM Z Series Mainframes on home computers:
http://www.hercules-390.eu/ -
2020-04-15 at 8:36 PM UTC in You guys call this good gay porn?Some of the elements are good. The whole thing is fucked. Especially the mouth(?).
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2020-04-15 at 8:34 PM UTC in You guys call this good gay porn?
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2020-04-15 at 8:32 PM UTC in 82% of the corona bailout money will go directly to the wealthy elite.They do when you cash out into local bank accounts.
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2020-04-15 at 8:23 PM UTC in You guys call this good gay porn?
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2020-04-15 at 8:16 PM UTC in This album doesn't show up when you google it - you have to use bing
Pretty ironic it's on youtube, no? -
2020-04-15 at 7:54 PM UTC in Anyone having really shit dreams?I dreamt I was a cobol programmer last night.
And most of my colleagues desks were empty, as they had died from Corona. I had moved to a desk which was better than my old desk, as it was nearer the coffee dock. -
2020-04-15 at 7:38 PM UTC in 82% of the corona bailout money will go directly to the wealthy elite.Yeah, sure thing. Good luck with having a payment processor and avoiding tax.
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2020-04-15 at 7:36 PM UTC in What is your opinion Jig
Originally posted by Jiggaboo_Johnson I've mentioned before when I was a young fella me lad there was a club in my hometown that had a "grab a granny" night on Thursdays…all the young horny dudes would go and all the horny grannies would go…that was a win win night.
Was it literally called that? How did they attract those two demographics? -
2020-04-15 at 7:33 PM UTC in 82% of the corona bailout money will go directly to the wealthy elite.
