| 
            plfsurf3d
          ( | x , | 
| y , | |
| zops , | |
| zp , | |
| nx , | |
| ny , | |
| opt , | |
| clevel , | |
| nlevel ); | 
      Plots a three-dimensional shaded surface plot within the
      environment set up by plw3d. The surface is defined by the
      two-dimensional function data accessed via the
      zpzpzopsplf2ops_c() should be used when
      zpPLFLT_MATRIX and
      plf2ops_grid_c(),
      plf2ops_grid_row_major(), and
      plf2ops_grid_col_major() should be used when the
      matrix of two-dimensional function data are organized within a
      PLfGrid2 structure as respectively two-dimensional
      row-major data, one-dimensional row-major data, and one-dimensional
      column-major data.  The nxnyoptclevelnlevelplsurf3d.
    
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.
zops
          (PLF2OPS
            Pointer to a plf2ops_t struct that
	    contains (amongst other function pointers) a pointer to a "get"
	    function that is used to evaluate the 2D function data required by
	    plfsurf3d.
          
zp
          (PLPointer
            Pointer to the two-dimensional function data in
	    the format required by the "get" function that is (indirectly) pointed
	    to by zops.  The various possibilities have
	    been discussed above, and examples of such use are given in
	    examples/c/x08c.c.
          
nx
          (PLINT
            Number of 
               values at
            which function is evaluated.
          x
            
ny
          (PLINT
            Number of 
               values at
            which function is evaluated.
          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.
          
This function is optionally used in C example 8.