anchor.diff:    For details on using mkl as a blas provider for python packages such as numpy,
     numexpr, scipy, etc., see the Python section of the NixPkgs manual.
   */
  -stdenvNoCC.mkDerivation rec {
  -  name = "mkl-${version}";
  -  version = "${date}.${rel}";
  -  date = "2019.3";
  -  rel = "199";
  +let
  +  # Release notes and download URLs are here:
  +  # https://registrationcenter.intel.com/en/products/
  +  version = "${year}.${spot}.${rel}";
  +  year = "2019";
  +
  +  # Darwin is pinned to 2019.3 because the DMG does not unpack; see here for details:
  +  # https://github.com/matthewbauer/undmg/issues/4
  +  spot = if stdenvNoCC.isDarwin then "3" else "5";
  +  rel = if stdenvNoCC.isDarwin then "199" else "281";
  +
  +  rpm-ver = "${year}.${spot}-${rel}-${year}.${spot}-${rel}";
  +
  +  # Intel openmp uses its own versioning, but shares the spot release patch.
  +  openmp-ver = "19.0.${spot}-${rel}-19.0.${spot}-${rel}";
  +
  +in stdenvNoCC.mkDerivation {
  +  pname = "mkl";
  +  inherit version;
   
     src = if stdenvNoCC.isDarwin
       then
  
positive.code:       })
      else
        (fetchurl {
          url = "http://registrationcenter-download.intel.com/akdlm/irc_nas/tec/15275/l_mkl_${version}.tgz";
          sha256 = "13rb2v2872jmvzcqm4fqsvhry0j2r5cn4lqql4wpqbl1yia2pph6";
        });
  
    nativeBuildInputs = if stdenvNoCC.isDarwin
      then
        [ undmg
          darwin.cctools
        ]
      else
        [ rpmextract ];
  
    buildPhase = if stdenvNoCC.isDarwin then ''
        for f in Contents/Resources/pkg/*.tgz; do
            tar xzvf $f
        done
    '' else ''
      rpmextract rpm/intel-mkl-common-c-${date}-${rel}-${date}-${rel}.noarch.rpm
      rpmextract rpm/intel-mkl-core-${date}-${rel}-${date}-${rel}.x86_64.rpm
      rpmextract rpm/intel-mkl-core-rt-${date}-${rel}-${date}-${rel}.x86_64.rpm
      rpmextract rpm/intel-openmp-19.0.3-${rel}-19.0.3-${rel}.x86_64.rpm
    '';
  
    installPhase = ''
  
negative.code:     homepage = https://software.intel.com/en-us/mkl;
      license = licenses.issl;
      platforms = [ "x86_64-linux" "x86_64-darwin" ];
      maintainers = with maintainers; [ bhipple ];
    };
  }
  