anchor.diff:  , blas
   , lapack
   , gfortran
  -, lapackSupport ? true }:
  +, suitesparse
  +, lapackSupport ? true
  +, kluSupport ? true }:
   
   assert (!blas.isILP64) && (!lapack.isILP64);
   
  
positive.code:     "-DSUNDIALS_INDEX_TYPE=int32_t"
      "-DLAPACK_ENABLE=ON"
      "-DLAPACK_LIBRARIES=${lapack}/lib/liblapack${stdenv.hostPlatform.extensions.sharedLibrary}"
    ];
  
    doCheck = true;
  
negative.code:   pname = "sundials";
    version = "5.3.0";
  
    buildInputs = [
      python
    ] ++ stdenv.lib.optionals (lapackSupport) [
      gfortran
      blas
      lapack
    ] 
    # KLU support is based on Suitesparse.
    # It is tested upstream according to the section 1.1.4 of
    # [INSTALL_GUIDE.pdf](https://raw.githubusercontent.com/LLNL/sundials/master/INSTALL_GUIDE.pdf)
    ++ stdenv.lib.optionals (kluSupport) [
      suitesparse
    ];
  
    nativeBuildInputs = [ cmake ];
  
    src = fetchurl {
  