use Perl

• Same thing only different (Score:1)

  by Mr. Muskrat (4572)

  I can't remember where I saw it first but I've always used:

  use constant PI => 4 * atan(1);
  • pi = 2*(pi/2) = 2*atan( 1/0 ) = 2*atan(+Inf) (Score:1)

    by ferreira (5993)

    use constant PI => 2 * atan2(1, 0);
• A more boring alternative... (Score:1)

  by itub (5708)

  #!/usr/bin/perl
  
  use Math::Trig;
  
  printf "Pi is %.12f\n", pi;
  • Re:A more boring alternative... (Score:2)

    by brian_d_foy (44)

    No need for Math::Triig there, since it actually gets pi() from Math::Complex, which implements it as

    sub pi () { 4 * CORE::atan2(1, 1) }
  • If you want a few more digits... (Score:1)

    by runrig (3385)

    use Math::NumberCruncher qw($PI);
    
    print PI, "\n";
    • Re:If you want a few more digits... (Score:2)

      by brian_d_foy (44)

      Math::NumberCruncher just hard-codes it. I can't post it here because there is some filter in Slashcode to block posts with "awful long string of letters". Feh

      $PI = new Math::BigFloat "3.141592653589793...";
      • Re:If you want a few more digits... (Score:1)

        by runrig (3385)

        Math::NumberCruncher just hard-codes it.

        Yeah, I knew that. So it was in a way an answer even more boring than the post I replied to :-) Nothing exciting like using log(-1) = -πi. But, having worked on the module, I just had to mention it :-)
        • Re:If you want a few more digits... (Score:2)

          by brian_d_foy (44)

          Now I'm kinda wondering if I can coerce Math::BigNum into my solution somehow so it gets a couple hundred decimal places....
• My personal favorite... (Score:2)

  by Damian (784)

  I understand that Brian was sharing a mathematical elegance with us, rather than actually trying to use PI, but since we're now headed off in that direction...

  When I need to approximate PI, I just remember the sequence [1 1 3 3 5 5], rearranging its two halves to get:

  my $PI = 355/113;

  which is correct to the first seven decimal places.

  That's sufficiently accurate to compute the circumference of the Earth from its radius with an error of about 3 metres (out of 40 million metres). Close enough for most e
  • Re:My personal favorite... (Score:2)

    by brian_d_foy (44)

    It's probably exactly the circumference of the earth if you pick the right spot. Short by 3 meters? Just move a bit off the mountain. :)
• Pi and e deeply interwoven (Score:1)

  by n1vux (1492)

  Thanks. I've always liked the equation

  e ** pi * i  + 1 = 0

  since it relates the 5 most important constants. I hadn't realized if one solved this equation for pi that all the coefficients were -1, that's so cool.

  --
  Bill
  # I had a sig when sigs were cool
  use Sig;