[postgis-users] location of point on linestring

[Alex Mayrhofer]

Hi,

I have a LINESTRING and a POINT which lies on (or "pretty close", see 
below*) the LINESTRING.

I need to know the relative position of the POINT on the LINESTRING 
(essentially the reverse of line_interpolate_point()).

Any idea how to do this?

thanks,

Alex
----
* the POINT _should_ be exactly on the LINESTRING because it comes from an 
intersect() operation.