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My question is really silly, I want to know what the meaning of this number displayed in my R environment, is it $2.2\times e^{-16}$?

user42912
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1 Answers1

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2.2e-16 means $ 2.2 \times 10^{-16}$. It is a shorthand convention for scientific notation hanging over, I think, originally from Fortran programming language.

user42912
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WA Don
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  • Thank you very much, that's weird, so the $e=10$ and the $-$ symbol doesn't mean the negative sign. – user42912 Jun 12 '20 at 13:53
  • Oh, the minus sign absolutely should have relevance here. @WADon probably just made a typo. 2.2e16 (also sometimes 2.2e+16) should be in reference to $2.2\times 10^{16}$ but 2.2e-16 would instead be $2.2\times 10^{-16}$ – JMoravitz Jun 12 '20 at 13:55
  • @JMoravitz I edited myself – user42912 Jun 12 '20 at 13:58
  • As for $e$ "equaling $10$", that is not quite accurate. It is more that it is being used as an operator, one which takes the number on the left and multiplies that by $10$ to the power of the number on the right... often for stylistic reasons and display limitations. – JMoravitz Jun 12 '20 at 14:01
  • Yes - a typo, for which apologies, and thanks for correcting. The 'e' just stands for exponent. The convention is also used by many calculators, being convenient when the space on the display is limited. – WA Don Jun 12 '20 at 14:47