In fact, I believe that you want ... 

(sort { $a <=> $b } (|CA|, |CB|, |CP|))[1]

[download]

where |...| means "the distance between these points". Of course, because the OP is working with points on a curved surface, he may need to work with great circle distances (and even then he has to allow for the planet not being spherical if he wants to be *really* precise) whereas lots of the solutions you'll find online assume that you're working on a plane. The assumption that the surface is a plane really breaks down once you're talking about distances of more than a few hundred km.

In reply to Re^2: Algorithm: point with N distance of a line between two other points by DrHyde
in thread Algorithm: point with N distance of a line between two other points by japhy

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.