| 
            plscmap1la
          ( | itype , | 
| npts , | |
| intensity , | |
| coord1 , | |
| coord2 , | |
| coord3 , | |
| alpha , | |
| alt_hue_path ); | 
      This is a variant of plscmap1l that supports alpha channel
      transparency. It sets cmap1 colors using a piece-wise linear
      relationship between cmap1 intensity index (0.0-1.0) and
      position in HLS or RGB color space (see the section called “Color Map1”)
      with alpha
itype
          (PLBOOLtrue: RGB, false: HLS.
npts
          (PLINTnumber of control points.
intensity
          (PLFLT_VECTORA vector containing the cmap1 intensity index (0.0-1.0) in ascending order for each control point.
coord1
          (PLFLT_VECTORA vector containing the first coordinate (H or R) for each control point.
coord2
          (PLFLT_VECTORA vector containing the second coordinate (L or G) for each control point.
coord3
          (PLFLT_VECTORA vector containing the third coordinate (S or B) for each control point.
alpha
          (PLFLT_VECTORA vector containing the alpha transparency value (0.0-1.0) for each control point.
alt_hue_path
          (PLBOOL_VECTOR
            A vector (with npts - 1 elements) containing
	    the alternative interpolation method Boolean value for each control point
	    interval.  (alt_hue_path[i] refers
            to the interpolation interval between the i and
            i + 1 control points).
          
      Redacted form: 
        plscmap1la(itype, intensity, coord1,
        coord2, coord3, alpha, alt_hue_path)
      
    
This function is used in example 30.