| 
            plsvect
          ( | arrowx , | 
| arrowy , | |
| npts , | |
| fill ); | 
      Set the style for the arrow used by plvect to plot vectors.
    
arrowx, arrowy
          (PLFLT_VECTOR
            A pair of vectors containing the x and y points
            which make up the arrow. The arrow is plotted by joining these
            points to form a polygon. The scaling assumes that the x and y
            points in the arrow lie in the range
            -0.5 <= x,y <= 0.5. If both
            arrowxarrowy
npts
          (PLINT
            Number of points in the vectors
            
               and
            arrowx
            
              .
          arrowy
            
fill
          (PLBOOL
            If 
               is true then the
            arrow is closed, if fill
            
              
            is false then the arrow is open.
          fill
            
      Redacted form: plsvect(arrowx, arrowy, fill)
    
This function is used in example 22.