clears a graphics window
xclear([window-id])
:window-id integer scalar or vector :
Without any argument, this function clears the current graphic figure by turning its visibility to ‘off’. Otherwise it clears the graphics figures whose numbers are included in the vector window-id. For example xclear(1:3) clears windows 1, 2 and 3. If one of the windows does not exist, then it is automatically created.
Function xclear is obsolete. To clear a figure, please use instead the clf function or the visible property.
`plot2d`_();
`scf`_();
`plot3d`_();
xclear(0); // clear the first graphic
xclear(); // clear the current figure