Replace Numerial Recipes LU decomp routines with LAPACK ones

.github/workflows/Intel.yml

@@ -37,7 +37,7 @@ jobs:
         rm GPG-PUB-KEY-INTEL-SW-PRODUCTS.PUB
         echo "deb https://apt.repos.intel.com/oneapi all main" | sudo tee /etc/apt/sources.list.d/oneAPI.list
         sudo apt-get update
-        sudo apt-get install intel-oneapi-openmp intel-oneapi-compiler-fortran-2023.2.1 intel-oneapi-compiler-dpcpp-cpp-and-cpp-classic-2023.2.1
+        sudo apt-get install intel-oneapi-openmp intel-oneapi-compiler-fortran-2023.2.1 intel-oneapi-compiler-dpcpp-cpp-and-cpp-classic-2023.2.1 intel-oneapi-mkl-devel-2023.2.0
         echo "source /opt/intel/oneapi/setvars.sh" >> ~/.bash_profile
 
     - name: checkout

.github/workflows/Linux.yml

@@ -33,11 +33,18 @@ jobs:
 
     - name: build
       run: |
+        sudo apt install libopenblas-serial-dev
         cd ip
         mkdir build 
         cd build
-        cmake -DCMAKE_PREFIX_PATH="~/" -DOPENMP=${{ matrix.openmp }} ${{ matrix.options }} ..
+        cmake -DCMAKE_PREFIX_PATH="~/" -DOPENMP=${{ matrix.openmp }} ${{ matrix.options }} -DCMAKE_INSTALL_PREFIX=~/install -DBLA_VENDOR=OpenBLAS ..
         make -j2 VERBOSE=1
+        make install
+        # Ensure that manual setting of '-DBLA_VENDOR=...' is reflected in output CMake config
+        if [ $(grep -c "BLA_VENDOR OpenBLAS" ~/install/lib/cmake/ip/ip-config.cmake) -eq 0 ]; then
+          echo "OpenBLAS not set as BLA_VENDOR in ip-config.cmake!"
+          exit 1
+        fi
 
     - name: test
       run: |

.github/workflows/Spack.yml

@@ -33,6 +33,7 @@ jobs:
 
     - name: spack-build-and-test
       run: |
+        sudo apt install libopenblas-serial-dev
         git clone -c feature.manyFiles=true https://github.com/spack/spack
         . spack/share/spack/setup-env.sh
         spack env create ip-env
@@ -43,9 +44,11 @@ jobs:
         precision=$(echo ${{ matrix.variants }} | grep -oP " precision=\K[4d8]")
         if [ "$precision" == "d" ]; then spack add grib-util@develop ; fi
         spack external find cmake gmake
+        spack external find --path /usr/lib/x86_64-linux-gnu/openblas-serial openblas
+        spack config add "packages:lapack:buildable:false"
         spack concretize
         # Run installation and run CTest suite
-        spack install --verbose --fail-fast --test root
+        spack install --fail-fast --test root
         # Run 'spack load' and check that key build options were respected
         spack load ip
         if [[ "${{ matrix.variants }}" =~ "+shared" ]]; then suffix="so" ; else suffix="a"; fi

.github/workflows/developer.yml

@@ -25,7 +25,7 @@ jobs:
     - name: Install Dependencies
       run: |
         sudo apt-get update
-        sudo apt-get install doxygen
+        sudo apt-get install doxygen libopenblas-dev
         python3 -m pip install gcovr
 
     - name: checkout

CMakeLists.txt

@@ -49,6 +49,8 @@ if(OPENMP)
   find_package(OpenMP REQUIRED COMPONENTS Fortran)
 endif()
 
+find_package(LAPACK REQUIRED)
+
 # Set compiler flags.
 if(CMAKE_Fortran_COMPILER_ID MATCHES "^(Intel|IntelLLVM)$")
   set(CMAKE_Fortran_FLAGS "-g -traceback -assume byterecl -fp-model strict -fpp -auto ${CMAKE_Fortran_FLAGS}")

README.md

@@ -31,8 +31,9 @@ Code Manager: [Alex Richert](mailto:[email protected])
 
 ### Prerequisites
 
-This package does not link to any other libraries, but requires CMake (version
-3.15+) to build.
+This package requires a BLAS/LAPACK library to provide several LU decomposition-related
+routines, and requires CMake (version 3.15+) to build. In spack-stack, OpenBLAS will
+be used as the provider of BLAS/LAPACK routines for all compilers.
 
 ### Installing
 

cmake/PackageConfig.cmake.in

@@ -13,6 +13,9 @@ if(@OPENMP@)
   find_dependency(OpenMP COMPONENTS Fortran)
 endif()
 
+set(BLA_VENDOR @BLA_VENDOR@)
+find_dependency(LAPACK)
+
 # The target name needs to be one that's built, even if the dependent
 # build does not use that version.
 if(@BUILD_4@)

docs/user_guide.md

@@ -19,6 +19,11 @@ where for certain regions of certain grids, floating point differences between
 field values. Some applications may therefore benefit from the use of 8-byte
 reals (libip_d or libip_8).
 
+NCEPLIBS-ip uses several BLAS/LAPACK routines in the splat() subroutine, and
+therefore requires an external BLAS/LAPACK provider. In practice, this should
+generally be OpenBLAS, which is the [spack-stack](https://github.com/JCSDA/spack-stack)
+BLAS/LAPACK provider.
+
 ## Interpolation
 
 ### Interpolation Methods

spack/package.py

@@ -65,6 +65,7 @@ class Ip(CMakePackage):
     depends_on("sp precision=4", when="@4.1:4 precision=4")
     depends_on("sp precision=d", when="@4.1:4 precision=d")
     depends_on("sp precision=8", when="@4.1:4 precision=8")
+    depends_on("lapack", when="@develop")
 
     def cmake_args(self):
         args = [
@@ -88,6 +89,16 @@ def cmake_args(self):
         if self.spec.satisfies("@5:"):
             args.append(self.define_from_variant("BUILD_DEPRECATED", "deprecated"))
 
+        if self.spec.satisfies("@develop"):
+            # Use the LAPACK provider set by Spack even if the compiler supports native BLAS
+            bla_vendors = {"openblas": "OpenBLAS"}
+            lapack_provider = self.spec["lapack"].name
+            if lapack_provider in bla_vendors.keys():
+                bla_vendor = bla_vendors[lapack_provider]
+            else:
+                bla_vendor = "All"
+            args.append(self.define("BLA_VENDOR", bla_vendor))
+
         return args
 
     def setup_run_environment(self, env):

src/CMakeLists.txt

@@ -14,7 +14,7 @@ ip_mercator_grid_mod.F90 ip_polar_stereo_grid_mod.F90
 ip_rot_equid_cylind_egrid_mod.F90 ip_rot_equid_cylind_grid_mod.F90
 ip_constants_mod.F90 ip_grids_mod.F90 ip_grid_factory_mod.F90
 ip_interpolators_mod.F90 earth_radius_mod.F90 polfix_mod.F90
-fftpack.F lapack_gen.F ncpus.F spanaly.f spdz2uv.f speps.f spfft1.f spffte.f
+fftpack.F ncpus.F spanaly.f spdz2uv.f speps.f spfft1.f spffte.f
 spfftpt.f splaplac.f splat.F splegend.f sppad.f spsynth.f sptezd.f sptez.f
 sptezmd.f sptezm.f sptezmv.f sptezv.f sptgpm.f sptgpmv.f sptgps.f sptgpsv.f
 sptgpt.f sptgptv.f sptrand.f sptran.f sptranf0.f sptranf1.f sptranf.f sptranfv.f
@@ -77,6 +77,7 @@ foreach(kind ${kinds})
   if(OpenMP_Fortran_FOUND)
     target_link_libraries(${lib_name} PUBLIC OpenMP::OpenMP_Fortran)
   endif()
+  target_link_libraries(${lib_name} PUBLIC LAPACK::LAPACK)
 
   list(APPEND LIB_TARGETS ${lib_name})
 

src/splat.F

@@ -64,7 +64,7 @@ SUBROUTINE SPLAT(IDRT,JMAX,SLAT,WLAT)
      $ 146.870307625, 150.011882457, 153.153458019, 156.295034268 /
       REAL:: DLT,D1=1.
       REAL AWORK((JMAX+1)/2,((JMAX+1)/2)),BWORK(((JMAX+1)/2))
-      INTEGER:: JHE,JHO,J0=0
+      INTEGER:: JHE,JHO,J0=0, INFO
       INTEGER IPVT((JMAX+1)/2)
       PARAMETER(PI=3.14159265358979,C=(1.-(2./PI)**2)*0.25)
 C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -133,8 +133,14 @@ SUBROUTINE SPLAT(IDRT,JMAX,SLAT,WLAT)
           BWORK(JS)=-D1/(4*(JS-1)**2-1)
         ENDDO
 
-        call ludcmp(awork,jho,jhe,ipvt)
-        call lubksb(awork,jho,jhe,ipvt,bwork)
+        ! Call LAPACK routines
+#if (LSIZE==4)
+        CALL SGETRF(JHO, JHO, AWORK, JHE, IPVT, INFO)
+        CALL SGETRS('N', JHO, 1, AWORK, JHE, IPVT, BWORK, JHO, INFO)
+#else
+        CALL DGETRF(JHO, JHO, AWORK, JHE, IPVT, INFO)
+        CALL DGETRS('N', JHO, 1, AWORK, JHE, IPVT, BWORK, JHO, INFO)
+#endif
 
         WLAT(1)=0.
         DO J=1,JHO
@@ -170,8 +176,14 @@ SUBROUTINE SPLAT(IDRT,JMAX,SLAT,WLAT)
           BWORK(JS)=-D1/(4*(JS-1)**2-1)
         ENDDO
 
-        call ludcmp(awork,jho,jhe,ipvt,d)
-        call lubksb(awork,jho,jhe,ipvt,bwork)
+        ! Call LAPACK routines
+#if (LSIZE==4)
+        CALL SGETRF(JHO, JHO, AWORK, JHE, IPVT, INFO)
+        CALL SGETRS('N', JHO, 1, AWORK, JHE, IPVT, BWORK, JHO, INFO)
+#else
+        CALL DGETRF(JHO, JHO, AWORK, JHE, IPVT, INFO)
+        CALL DGETRS('N', JHO, 1, AWORK, JHE, IPVT, BWORK, JHO, INFO)
+#endif
 
         WLAT(1)=0.
         DO J=1,JHO