Geometry app warnings

[Alberto Candel]

In the Geometry Symbolic View I type

GA:=point(4, 3+e^(2*pi*i/5),3+e^(4*pi*i/5),3+e^(6*pi*i/5),3+e^(8*pi*i/5))
GB:=convexhull(GA)

then hit the Plot key and obtain a sequence of warnings like

Warning! Algebraic extension not implemented yet for poly[-1,0,30,-40,-5]

The numbers in brackets change.

Sometimes it stops and displays GB, which is a regular pentagon.

I cannot find an explanation for that warning in the User Guide. Any help? Thank you.

A.

[parisse]

This is because the convexhull is computed exactly, replacing exp() by sqrt, and simplifying in an unique algebraic extension of the rationals. You can avoid the warnings by using approx data.

Code:


GA:=evalf(4, 3+e^(2*pi*i/5),3+e^(4*pi*i/5),3+e^(6*pi*i/5),3+e^(8*pi*i/5));
GB:=convexhull(GA);