(A+Reflect(A, y=0))/2 (projection point on xz-plane) switched onto x-axis after saving and reopen

Shamrock shared this problem 2 years ago
Not a Problem

To get the projection of an arbitrary ponint A onto xz-plane can be got using A_{xz}=(A+Reflect(A, y=0)). This gives a correct result after input. However, the point happens to be switched onto the x-axis (i.e. the position of (A+Reflect(A, xAxis))/2 ).

Inputing the same command, and another point is created at the correct position.

This bug have been existing since version 5 or earlier.

The GeoGebra version I am currently using is "GeoGebra 6.0.546.0" on 64-bit Linux installed by the .deb file downloaded from the official site.

Comments (2)


y=0 is the xAxis if graphics view is active and

y=0 is the xz plane if 3Dgraphics is active

when GG open file the active view is graphics so try A_{xz}=(A+Reflect(A, y+0z=0))/2

or A_{xz}=(x(A),0,z(A))


Some other syntaxes you can try

(A+Reflect(A, Plane((0,0,0),(1,0,1),(1,0,-1))))
(A+Reflect(A, xAxis))

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