anchor.diff:  
     buildInputs = [ gfortran readline ncurses perl flex texinfo qhull libX11
       graphicsmagick pcre pkgconfig mesa fltk zlib curl openblas libsndfile
  -    fftw fftwSinglePrec qrupdate ]
  +    fftw fftwSinglePrec qrupdate arpack libwebp ]
       ++ (stdenv.lib.optional (qt != null) qt)
       ++ (stdenv.lib.optional (qscintilla != null) qscintilla)
       ++ (stdenv.lib.optional (ghostscript != null) ghostscript)
  
positive.code:     ++ (stdenv.lib.optional (jdk != null) jdk)
      ++ (stdenv.lib.optional (gnuplot != null) gnuplot)
      ++ (stdenv.lib.optional (python != null) python)
      ;
  
    doCheck = true;
  
    enableParallelBuilding = true;
  
  
negative.code:       "--with-blas=openblas"
        "--with-lapack=openblas"
      ]
      ++ stdenv.lib.optional openblas.blas64 "--enable-64"
      ++ stdenv.lib.optionals stdenv.isDarwin ["--with-x=no"]
      ;
  
    # Keep a copy of the octave tests detailed results in the output
    # derivation, because someone may care
  