Default ENABLE_LAPACK as OFF (#825)

### Before submitting

Please complete the following checklist when submitting a PR:

- [ ] All new features must include a unit test.
If you've fixed a bug or added code that should be tested, add a test to
the
      [`tests`](../tests) directory!

- [ ] All new functions and code must be clearly commented and
documented.
If you do make documentation changes, make sure that the docs build and
      render correctly by running `make docs`.

- [ ] Ensure that the test suite passes, by running `make test`.

- [x] Add a new entry to the `.github/CHANGELOG.md` file, summarizing
the
      change, and including a link back to the PR.

- [x] Ensure that code is properly formatted by running `make format`. 

When all the above are checked, delete everything above the dashed
line and fill in the pull request template.


------------------------------------------------------------------------------------------------------------

**Context:**

[SC-70045]

**Description of the Change:**

**Benefits:**

**Possible Drawbacks:**

**Related GitHub Issues:**

---------

Co-authored-by: ringo-but-quantum <[email protected]>
Co-authored-by: Vincent Michaud-Rioux <[email protected]>
Co-authored-by: Ali Asadi <[email protected]>

.github/CHANGELOG.md

@@ -15,6 +15,9 @@
 
 ### Improvements
 
+* `ENABLE_LAPACK` is off by default for all Lightning backends.
+  [(#825)](https://github.com/PennyLaneAI/pennylane-lightning/pull/825)
+
 * Update `LightingQubit.preprocess` to work with changes to preprocessing for mid-circuit measurements.
   [(#812)](https://github.com/PennyLaneAI/pennylane-lightning/pull/812)
 

.github/workflows/tests_lgpu_cpp.yml

@@ -61,9 +61,10 @@ jobs:
     strategy:
       matrix:
         pl_backend: ["lightning_gpu"]
+        enable_lapack: ["OFF", "ON"]
         cuda_version: ["12"]
 
-    name: C++ Tests (${{ matrix.pl_backend }}, cuda-${{ matrix.cuda_version }})
+    name: C++ Tests (${{ matrix.pl_backend }}, cuda-${{ matrix.cuda_version }}, enable_lapack=${{ matrix.enable_lapack }})
     runs-on:
       - ubuntu-22.04
       - self-hosted
@@ -136,6 +137,7 @@ jobs:
             -DCUQUANTUM_SDK=$(python -c "import site; print( f'{site.getsitepackages()[0]}/cuquantum')")\
             -DBUILD_TESTS=ON \
             -DENABLE_PYTHON=OFF \
+            -DENABLE_LAPACK=${{ matrix.enable_lapack }} \
             -DPL_BACKEND=${{ matrix.pl_backend }} \
             -DCMAKE_CXX_COMPILER=$(which g++-$GCC_VERSION) \
             -DENABLE_COVERAGE=ON \

.github/workflows/tests_linux_cpp.yml

@@ -48,11 +48,12 @@ jobs:
         pl_backend: ["lightning_qubit"]
         enable_kernel_omp: ["OFF", "ON"]
         enable_kernel_avx_streaming: ["OFF", "ON"]
+        enable_lapack: ["OFF", "ON"]
         exclude:
         - enable_kernel_omp: OFF
           enable_kernel_avx_streaming: ON
     timeout-minutes: 60
-    name: C++ Tests (${{ matrix.pl_backend }}, ENABLE_KERNEL_OMP=${{ matrix.enable_kernel_omp }}, ENABLE_KERNEL_AVX_STREAMING=${{ matrix.enable_kernel_avx_streaming }})
+    name: C++ Tests (${{ matrix.pl_backend }}, ENABLE_KERNEL_OMP=${{ matrix.enable_kernel_omp }}, ENABLE_KERNEL_AVX_STREAMING=${{ matrix.enable_kernel_avx_streaming }}), ENABLE_LAPACK=${{ matrix.enable_lapack }})
     runs-on: ${{ needs.determine_runner.outputs.runner_group }}
 
     steps:
@@ -75,6 +76,7 @@ jobs:
               -DCMAKE_BUILD_TYPE=Debug \
               -DBUILD_TESTS=ON \
               -DENABLE_PYTHON=OFF \
+              -DENABLE_LAPACK=${{ matrix.enable_lapack }} \
               -DPL_BACKEND=${{ matrix.pl_backend }} \
               -DCMAKE_CXX_COMPILER=$(which g++-$GCC_VERSION) \
               -DENABLE_COVERAGE=ON \

.github/workflows/tests_lkcuda_cpp.yml

@@ -111,8 +111,9 @@ jobs:
         pl_backend: ["lightning_kokkos"]
         exec_model: ["CUDA"]
         kokkos_version: ["4.3.01"]
+        enable_lapack: ["OFF", "ON"]
 
-    name: C++ Tests (${{ matrix.pl_backend }}, kokkos-${{ matrix.kokkos_version }}, model-${{ matrix.exec_model }})
+    name: C++ Tests (${{ matrix.pl_backend }}, kokkos-${{ matrix.kokkos_version }}, model-${{ matrix.exec_model }}), enable_lapack-${{ matrix.enable_lapack }}
     runs-on:
       - ${{ matrix.os }}
       - self-hosted
@@ -190,6 +191,7 @@ jobs:
             -DCMAKE_BUILD_TYPE=Debug \
             -DBUILD_TESTS=ON \
             -DENABLE_PYTHON=OFF \
+            -DENABLE_LAPACK=${{ matrix.enable_lapack }} \
             -DCMAKE_PREFIX_PATH=${{ github.workspace }}/Kokkos \
             -DPL_BACKEND=${{ matrix.pl_backend }} \
             -DCMAKE_CXX_COMPILER=$(which g++-$GCC_VERSION) \

.github/workflows/tests_windows_cpp.yml

@@ -131,7 +131,6 @@ jobs:
               -DBUILD_TESTS=ON `
               -DENABLE_OPENMP=OFF `
               -DENABLE_PYTHON=OFF `
-              -DENABLE_LAPACK=OFF `
               -DENABLE_GATE_DISPATCHER=OFF `
               -DPL_BACKEND=${{ matrix.pl_backend }} `
               -DENABLE_WARNINGS=OFF

CMakeLists.txt

@@ -47,7 +47,7 @@ option(ENABLE_WARNINGS "Enable warnings" ON)
 option(ENABLE_NATIVE "Enable native CPU build tuning" OFF)
 option(ENABLE_PYTHON "Enable compilation of the Python module" ON)
 
-option(ENABLE_LAPACK "Enable compilation with scipy/LAPACK" ON)
+option(ENABLE_LAPACK "Enable compilation with scipy/LAPACK" OFF)
 
 # OpenMP
 find_package(OpenMP)