ST_InterpolatePoint returns empty M value

[arho]

If the interpolated point is directly on the line, M is 0:

Example - point not on line, correct M value: SELECT ST_InterpolatePoint('LINESTRING M (0 0 0, 10 0 20)', 'POINT(5 5)');

st_interpolatepoint

---

10

Example - point on line, M value is 0: SELECT ST_InterpolatePoint('LINESTRING M (0 0 0, 10 0 20)', 'POINT(5 0)');

st_interpolatepoint

---

0

Expected Result: 10

Version information: POSTGIS="2.0.0 r9605" GEOS="3.3.2-CAPI-1.7.2" PROJ="Rel. 4.7.1, 23 September 2009" GDAL="GDAL 1.9.0, released 2011/12/29" LIBXML="2.7.8" RASTER PostgreSQL 9.1.2 on i686-pc-linux-gnu, compiled by gcc-4.6.real (Debian 4.6.2-4) 4.6.2, 32-bit

[strk]

I shall notice that the lwgeom_interpolate_point doesn't have a unit test (and I confirm the bug)

[pramsey]

Fixed in 2.0 at r9954 and in trunk.