Help! How to access App's variables?

[cyrille de brébisson]

Hello,

Geometry is such a poor, misunderstood app... sniff...

What most people do not understand is that a geometry variable GC, for example does NOT contain line(GA, GB), but it contains the result of the evaluation of line(GA, GB). Which happen to be a graphical CAS command describing a line.

When you go in the geometry symbolic view, what you see is a PROGRAM! and the execution of that program, sequentially, from top to bottom, does generate/assign values to variables, these values containing graphical descriptions.

Each time you change/modify a 'point', the whole program is re-evaluated.

This is why you can not affect an instruction value to GA (well, you can but it will not persist long), because on next evaluation of the program whatever you placed there will be overridden.

As stated above, this is what the "Instruction" app variable is for. To let you interract with the geometry program.

In your case, assuming that geometry is the current app, this line should do it.

Instruction:="GA:= point(1.,1.); // c(FF000000) v(1) \nGB:= point(5.,6.); // c(FF000000) v(1) \nGC:= segment(GB,GA); // c(FF000000) v(1) \n"


Please read the help for Instruction for more information.
Regards,
Cyrille