anchor.diff:      hue2 = 360.0
       light1 = 0.0
       light2 = 100.0
  -    chroma1 = 50.0
  -    chroma2 = 50.0
  +    chroma1 = 40.0
  +    chroma2 = 40.0
       ncolors = 10
       vrb = 0
       narg = iargc()
  
positive.code: subroutine usage(str)
      implicit none
      character(len=*) :: str
      if (str.ne.'') then
          write(0,*) str
          write(0,*)
      endif
      write(0,*) 'Usage: colortool -perceptual OPTION [-hue H1,H2] [-lightness L1,L2] [-chroma C1,C2] [-ncolors N] [-v verbose]'
      write(0,*) '-perceptual OPTION      Generate a perceptually linear color scheme'
      write(0,*) '                            spiral: rotate through hues in LCH space (r->o->y->g->b->p)'
      write(0,*) '                            linear: draw line through LAB space'
      write(0,*) '-hue H1,H2              Starting and ending hues (default: 0,360)'
      write(0,*) '                            0=360=magenta, 30=red, 45=orange, 90=yellow, 150=green, 270=blue, 330=purple'
      write(0,*) '-lightness L1,L2        Starting and ending hues (default: 0,100)'
      write(0,*) '-chroma C1,C2           Starting and ending chroma (default: 50,50)'
      write(0,*) '                            0=grey, max value depends on hue (program limits chroma to max value automatically)'
      write(0,*) '-ncolors N              Number of colors (default: 10)'
      write(0,*) '-verbose                Turn on verbose mode'
      stop
  return
  end
  
negative.code:     endif
  end
  
  !~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~!
  
  subroutine formatrgb(red,grn,blu,rgbstring)
      implicit none
      real :: red,grn,blu
  