### 10.1 Predefined variables

Predefined variables related to 3D representation:

• theta and phi: used in the calculations of the projections on the screen plane, respectively initialized to $\pi$/6 and $\pi$/3, the first one is the longitud and the second is the colatitude. Those are also editable using a button in the toolbar.
• sep3D: constant initialized to Re(jump)-i, used as delimiter for the graphics elements in the command Build3D.
• AngleStep: represents the angular step when rotating a 3D object using the arrows buttons. initialized to $\pi ∕36$ (ie: 5 degrees).
• Origin: origin, initialized to [0,0].
• vecI: 1st base vector, initialized to [1,0].
• vecJ: 2nd base vector, initialized to [i,0].
• vecK: 3rd base vector, initialized to [0,1].
• For the 3D window: Xinf (=-5), Xsup (=5), Yinf (=-5), Ysup (=5), Zinf (=-5) and Zsup (=5).
• HideStyle: initialized to dotted, for the style of the hidden edges,
• HideWidth: initialized to Nil, for the thickness of the hidden edges,
• HideColor: initialized to Nil, for the color of the hidden edges.