in reply to Re^7: Data visualisation.
in thread Data visualisation.

Nothing, really. It just mentions them.... I'll still calculate the intersection point where the lines *would* meet, were they long enough.

Oh, okay.

Though I have to say that it sounds like you are now performing 3 "triangle inequality" checks for every possible triangle (for my 17 node dataset that is 3*15! or nearly 4 Trillion additions and 4 Trillion comparisons) for no real purpose. Ie pure make-work....

For Dirk80's 24 node dataset, that rises to 1.8 trillion trillion redundant calculations.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

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Re^9: Data visualisation.
by roboticus (Chancellor) on Jan 05, 2014 at 18:13 UTC

    BrowserUk:

    We're only picking three points for each triangle, and the point order doesn't matter, so the number of calls to chk_triangle_inequality during the exhaustive check for your dataset is n!/((n-3)!*3!). For your dataset, it's 680 calls, and 2024 for Dirk80's dataset. If it were trillions of checks, I'd've pressed ^C long before it ended. ;^D

    Currently the check is pointless busywork, but since TSP problem is interesting to me, and printing interesting clues might spur ideas, so I threw it in for fun. I frequently litter my programs with print statements showing intermediate steps, or call functions whose results may be interesting. I delete it when it proves valueless to me, and then clean it up when I'm through. But I can't always predict beforehand which functions I'll find to be junk.

    For example, when I was playing with your Bloom filter example, I put various print statements in my program, and noticed that one of the values was approaching an "interesting" value, allowing me to figure out the distributions.

    Update: As AM said, wrong formula! Fixed.

    ...roboticus

    When your only tool is a hammer, all problems look like your thumb.

[reply]
      Strange ... wrong formula but correct values???

      s/2/3/ ;-)

[reply]
      so the number of calls to chk_triangle_inequality during the exhaustive check for your dataset is n!/((n-2)!*2!). For your dataset, it's 680 calls, and 2024 for Dirk80's dataset.

      Indeed. I found completely the wrong formula.

      (BTW: it is simply all combinations of 3 from N; so if you have a calculator with an nCr button ... )

      With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
Re^9: Data visualisation.
by Anonymous Monk on Jan 05, 2014 at 10:17 UTC
    nosense!
[reply]

      Argh! You're right. For Dirk80's dataset it is only 1.1 billion trillion. My mistake.

      With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
        try again...
[reply]

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