The Vancouver Stock Exchange’s Rounding Error that Dropped the Market Value by Half

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Sun Jan 12 2020 17:40:37 GMT+0000 (Coordinated Universal Time)

Saved by @chrissyjones #historicalcode #numbers

- return floor(value)
+ return round(value)

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In early 1982, the Vancouver Stock Exchange unveiled an electronic stock index initially pegged to a value of 1,000 points. In two years it dropped to half its original value—a confusing trend amid the bull market of the early 1980s. An investigation revealed that the calculations of the index were wrong in just one command, using floor() rather than round(). This command meant that instead of rounding to the third decimal place, the value was being truncated. (Digital computers necessarily have finite resolution, which necessitates rounding or truncation.) So if the index was calculated as 532.7528, it was stored as 532.752, rather than rounded up to 532.753. Over the course of thousands of calculations a day, this seemingly minor difference—essentially rounding down every single time—amounted to a dramatic loss in value. The programming mistake was finally fixed in November 1983, after the index closed around 500 on a Friday. It reopened on Monday at over 1,000, its lost value restored. —Lav Varshney, assistant professor, University of Illinois at Urbana-Champaign

https://slate.com/technology/2019/10/consequential-computer-code-software-history.html

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#historicalcode #numbers

The Vancouver Stock Exchange’s Rounding Error that Dropped the Market Value by Half

- return floor(value)
+ return round(value)

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Google’s PageRank Algorithm from 1996 - the origin of internet search

import numpy as np

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The Code that made Bitcoin - exist and really secure

double AttackerSuccessProbability(double q, int z)
{
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POODOO    INHINT
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//PASSWORD CRACKER FUNCTION

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Summary from Microsoft BASIC 6502 Original Source Code from 1978 written by Bill Gates and Paul Allen

================================================================================================
FILE: "david mac g5 b:m6502.asm"
================================================================================================

000001  TITLE   BASIC M6502 8K VER 1.1 BY MICRO-SOFT
[...]
006955          END     $Z+START

End of File -- Lines: 6955 Characters: 154740

SUMMARY:

  Total number of files : 1
  Total file lines      : 6955
  Total file characters : 154740
  
  

PAUL ALLEN WROTE THE NON-RUNTIME STUFF.
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MONTE DAVIDOFF WROTE THE MATH PACKAGE.

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Converting float numbers to integer in Python

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send(to, from, count)
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The Vancouver Stock Exchange’s Rounding Error that Dropped the Market Value by Half

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