 ZOOM                                                                Menu: VIEW
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 Zooms in on a specified window or by a specified factor.
 (A nested command)

         1. (CHAR) options: w-window, f-factor <w>
      if reply is `w'
         2. (POINT) first point of zoom
         3. (POINT) opposite point of zoom (press <ENTER> for another first pt)
      if reply is `f'
         2. (NUM) factor (greater than 1) <2>

 Description:
 This command zooms in on the geometric model.
 Select one of the two options: zoom by specifying a window on the screen (`w'
 the default), or by specifying a zoom factor (`f'). If you selected the window
 option, pick two opposite points of the window. The specified area is enlarged
 to fill the screen, and the scale is modified appropriately. If you pick
 an incorrect position for the first point, press <ENTER> and you will be
 prompted for a new first point.


 If you selected the zoom factor option, specify a value greater than 0 (the
 default is 2). The current scale will be multiplied by this factor. The
 location of the screen center point remains fixed.

         Examples: \zoom w 4 4 0 8 8 0

 Result: The square area defined between 4 4 0 and 880 fills the screen and the
 scale is adjusted.

                   \zoom f 4

 Result: If the current scale was 1:100, the new scale will be 1:25. The
 location of the screen center point remains fixed.
