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Sin/Cos/Tan question

  1. Aug 17, 2004 #1
    I've been working with the trigonometric ratios for a long time now and was wondering, when you type sin(x), where x is any number and hit the equals sign, what function is actually being applied to the number?
  2. jcsd
  3. Aug 17, 2004 #2
    I guess that would be
    [tex]\sin(x)=\sum_n \left( \frac{x^{4n+1}}{(4n+1)!}-\frac{x^{4n+3}}{(4n+3)!} \right)[/tex]
    to finite order, by first reducing to the fundamental [tex] [-\pi;\pi] [/tex]
  4. Aug 17, 2004 #3


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    For a very long time, I thought that calculators (and computers) used the Taylor's series (what humanino gives is a variation on that) for ex, sin(x), cos(x), etc. but I have been informed that all modern calculations use the "CORDIC" algorithm.

    Here is a link to an explanatory website:
    Last edited by a moderator: Aug 17, 2004
  5. Aug 17, 2004 #4
    now, that's clever ! Anyway, I had doubt about the series. Thanks Hallsoflvt. This algorithm makes me thinf of FFT.
    (well actually it is much simpler)
  6. Aug 17, 2004 #5
    Interesting, thanks.
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