void rotate (isrot) BOTHPLT.C Level 1
int isrot = 0 if page is upright (default). 
= 1 if page is rotated 90 degrees.
rotate() rotates the page 90 degrees (clockwise). It must be called before a call to page() if the rotation of the page is to be changed. The top of the plot will be on the right of the screen. 

In GUI environments, the plot will always be upright on the screen and the window frame will be resized to the correct aspect ratio. To make this more intuitive, we have defined two macros that may be 
used instead of calls to rotate()
     LANDSCAPE is equivalent to rotate(0)
     PORTRAIT is equivalent to rotate(1)