[postgis] BUG FIX: length_spheroid()

Dave Blasby dblasby at refractions.net
Fri Dec 21 14:04:32 PST 2001


This function uses an iterative solution to find the distance between
two points on an ellipsoid.
Unfortunately, it doesnt always converge and leads to an infinite loop.

Here's an example of input that causes it to "crash":

LINESTRING(-123.0506307 49.0912044,-123.0473293 49.0912039)

with

'SPHEROID["GRS_1984",6378137.0,298.257223563 ]'

I've reported the bug to the folks who originally wrote the code and
postgis now forces it to stop iterating after
1000 iterations.

Its in the CVS version, but read the next message before you download
it.
dave

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