areaint is not invariant with respect to longitude

I am using areaint after using polybool('intersection',... and get inconsistent results, so I tried to evaluate areas on polygons in example 2 in http://www.mathworks.com/help/toolbox/map/ref/polybool.html. I multiplied Ax Ay and Bx By by 10 and treated as if the coordinates were long lat. I found out that areas are changing rather dramatically when rotating longitude. Does anyone have an idea, what is wrong?

Answer 1

[Walter Roberson]

Is it latitude or longitude that makes the difference? I would expect that kind of effect for latitude.

[Marie-Louise]

It is both latitude and longitude. I have plotted the differences for longitude and it looks strange.

[Walter Roberson]

What range of values are you using?

The description of areaint() indicates that it is sensitive to the distance between the points; the examples show that using a finer grid can get a better answer.

[Marie-Louise]

Yes, but still I wonder why the areas changes when moving a figure in longitudinal direction.

I wonder if I should use a different approach -transforming to an area invariant projection and evaluate area.

[C. Gutierrez]

Maybe I misunderstand your question - but wouldn't you expect that area would vary depending on region of the globe, hence the need for the various projection systems? Due to the flattened nature of Earth, we should expect it to vary more along latitude than longitude but both movements should change the area.