Name:         PGPT

Purpose:      draw several graph markers

Category:     GRAPHICS

File:         pgplot.src

Author:       T.J. Pearson

Use:          see description below.

Description:

            SUBROUTINE PGPT (N, XPTS, YPTS, SYMBOL)
            INTEGER N
            REAL XPTS(*), YPTS(*)
            INTEGER SYMBOL
      
       Primitive routine to draw Graph Markers (polymarker). The markers
       are drawn using the current values of attributes color-index,
       line-width, and character-height (character-font applies if the symbol
       number is >31).  If the point to be marked lies outside the window,
       no marker is drawn.  The "pen position" is changed to
       (XPTS(N),YPTS(N)) in world coordinates (if N > 0).
      
       Arguments:
        N      (input)  : number of points to mark.
        XPTS   (input)  : world x-coordinates of the points.
        YPTS   (input)  : world y-coordinates of the points.
        SYMBOL (input)  : code number of the symbol to be drawn at each 
                          point:
                          -1, -2  : a single dot (diameter = current
                                    line width).
                          -3..-31 : a regular polygon with ABS(SYMBOL)
                                    edges (style set by current fill style).
                          0..31   : standard marker symbols.
                          32..127 : ASCII characters (in current font).
                                    e.g. to use letter F as a marker, let
                                    SYMBOL = ICHAR('F'). 
                          > 127  :  a Hershey symbol number.
      
       Note: the dimension of arrays X and Y must be greater than or equal
       to N. If N is 1, X and Y may be scalars (constants or variables). If
       N is less than 1, nothing is drawn.

Updates:      Oct 16, 1998: JPT automatically extracted from source.