| 
            plsurf3dl
          ( | x , | 
| y , | |
| z , | |
| nx , | |
| ny , | |
| opt , | |
| clevel , | |
| nlevel , | |
| indexxmin , | |
| indexxmax , | |
| indexymin , | |
| indexymax ); | 
      This variant of plsurf3d (see that function's documentation for
      more details) should be suitable for the case where the area of
      the xyzindexxminindexxmaxindexyminindexymax
x
          (PLFLT_VECTORA vector containing the x coordinates at which the function is evaluated.
y
          (PLFLT_VECTORA vector containing the y coordinates at which the function is evaluated.
z
          (PLFLT_MATRIX
	    A matrix containing function values to plot.  Should have
	    dimensions of nx by ny.
          
nx
          (PLINT
            Number of x
ny
          (PLINT
            Number of y
opt
          (PLINTDetermines the way in which the surface is represented. To specify more than one option just add the options, e.g. FACETED + SURF_CONT
                  
                    : Network
                  of lines is drawn connecting points at which function is
                  defined.
                opt=FACETED
                  
                  
                    : A contour
                  plot is drawn at the base XY plane using parameters
                  opt=BASE_CONT
                  nlevel and clevel.
                
                  
                    : A contour
                  plot is drawn at the surface plane using parameters
                  opt=SURF_CONT
                  nlevel and clevel.
                
                  
                    : draws a curtain
                  between the base XY plane and the borders of the plotted function.
                opt=DRAW_SIDES
                  
                  
                    :
                  the surface is colored according to the value of Z; if
                  opt=MAG_COLOR
                  MAG_COLOR is not used, then
                  the surface is colored according to the intensity of the
                  reflected light in the surface from a light source whose
                  position is set using pllightsource.
                
clevel
          (PLFLT_VECTORA vector containing the contour levels.
nlevel
          (PLINT
            Number of elements in the clevel vector.
          
indexxmin
          (PLINT
            The index value (which must be ≥ 0) that corresponds to
            the first 
               index where
            x
            
               is defined.
          z
            
indexxmax
          (PLINT
            The index value (which must be ≤
            
              ) which corresponds (by
            convention) to one more than the last
            nx
            
               index value where
            x
            
               is defined.
          z
            
indexymin
          (PLINT_VECTOR
            A vector containing the yyzxindexxminindexxmax - 1indexyminindexxmax
indexymax
          (PLINT_VECTOR
            A vector containing the
	    ynyyzxindexxminindexxmax - 1indexymaxindexxmax
      Redacted form: 
        plsurf3dl(x, y, z, opt, clevel,
        indexxmin, indexymin, indexymax)
      
    
This function is used in example 8.