plvpor: Specify viewport using coordinates

Device-independent routine for setting up the viewport. This defines the viewport in terms of normalized subpage coordinates which run from 0.0 to 1.0 (left to right and bottom to top) along each edge of the current subpage. Use the alternate routine plsvpa in order to create a viewport of a definite size.

xmin (PLFLT, input) The normalized subpage coordinate of the left-hand edge of the viewport. xmax (PLFLT, input) The normalized subpage coordinate of the right-hand edge of the viewport. ymin (PLFLT, input) The normalized subpage coordinate of the bottom edge of the viewport. ymax (PLFLT, input) The normalized subpage coordinate of the top edge of the viewport.

Redacted form: plvpor(xmin, xmax, ymin, ymax)

This function is used in examples 2,6-8,10,11,15,16,18,21,23,24,26,27,31.