[R-sig-Geo] areaint in Matlab vs. areaPolygon or areapl in R

[c.gutierrez]

I'm at a bit of a loss here, because if I test a real-life case, I get the
same results from the Online Geodesic Planimeter page you indicated as I get
from Matlab's areaint() = 162606.10366468679.

>From 
"Enter the vertices as latitude longitude pairs, one per line: "
36.96353 -0.4164187
36.96273 -0.4161722
36.96179 -0.4158859
36.96247 -0.4113503
36.96429 -0.4115961
36.96484 -0.4118041
36.96581 -0.4119622
36.96562 -0.4133627
36.96516 -0.4167762
36.96502 -0.4167687
36.96459 -0.4167097
36.96367 -0.4164608
36.96353 -0.4164187

Results:

    STATUS             = OK
    number of vertices = 13
    Perimeter (m)      = 1604.00781596
    area (m^2)         = 162516.702

This seems to suggest that it's the R function(s) that are off, if we take
Kearney's result to be the best approximation of the truth. Here's what I
get from the geosphere and splancs functions:
> areaPolygon(coords)
[1] 205029.5
 ... or ...
> areapl(coords.proj4m) #projected using "+proj=utm +zone=36 +ellps=clrk80
> +units=m +towgs84=-179.1,-44.7,-302.6 +no_defs"
[1] 203332.68



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