Re^2: Algorithm: point with N distance of a line between two other points


P is for Practical
	PerlMonks

Re^2: Algorithm: point with N distance of a line between two other points

by japhy (Canon)

on Nov 04, 2010 at 01:23 UTC ( [id://869380]=note: print w/replies, xml )

Need Help??

in reply to Re: Algorithm: point with N distance of a line between two other points
in thread Algorithm: point with N distance of a line between two other points

Yes, LR, my initial idea had been to solve a quadratic equation and test the values of the two solutions. But I've found that Math::Geometry::Planar's DistanceToSegment() function works well with cartesian coordinates.

I'm facing two problems, though: 1) I'm starting with lat/long coordinates, not cartesian coordinates; and 2) I'd like the algorithm to run in a mysql query. I already have a GEO_DISTANCE(lat1,lng1,lat2,lng2) function in mysql, and I can reproduce DistanceToSegment() in mysql, but I'm not confident that DistanceToSegment() works appropriately with lat/long coordinates. Any ideas here?

Jeff japhy Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and perl hacker
Nos autem praedicamus Christum crucifixum (1 Cor. 1:23) - The Cross Reference (My Blog)

Comment on Re^2: Algorithm: point with N distance of a line between two other points

Replies are listed 'Best First'.

Re^3: Algorithm: point with N distance of a line between two other points
by Limbic~Region (Chancellor) on Nov 04, 2010 at 02:05 UTC

japhy

this

Regarding your statement about MySQL query - I assume have no idea what built-in trig functions are available and I don't envy re-implementing them from scratch. If this were Pg, you could just use plperl and use the module that did what you wanted :-)

Cheers - L~R

[reply]

In Section Seekers of Perl Wisdom