Question on Geom App

[Jean-Michel]

Hello all

Why is_perpendicular() and his sister function is_orthogonal() do not give a result when dealing with segments whereas they do for lines?
Btw, why two functions for one single use ? Or do I miss something?

[parisse]

is_perpendicular(segment(0,i),segment(0,1)) works, like for lines.
is_perpendicular and is_orthogonal are different in 3d geometry (not available on the Prime).

[Jean-Michel]

Hello Bernard and thanks for your prompt answer.

My problem is the following, with entities defined below:
Two segments, GI and GH, each one defined by geometrical points.
angle(GI,GH) returns -90 (°, correct according to my drawing)
is_perpendicular(GI,GH) returns 0, instead of 1
is_orthogonal(GI,GH) returns 0, instead of 1
Same test on lines defined by same point returns 1.

[parisse]

I can not answer without the full construction. It might be because of rounding errors (with numeric data) or because you are using symbolic data that are not automatically simplified in is_perpendicular.
If you want more info, try your figure with Xcas in a geometry 2d level, then use the Save commandlines in the Fig menu to save the commandline in a file and copy/paste the content of the file, that way I can easily reproduce the problem and help you (unfortunately the Prime does not provide a similar feature to save/restore a figure from commandlines, you must use Xcas for that).