Add missing tests for serial Trsm

Signed-off-by: Yuuichi Asahi <[email protected]>

batched/dense/unit_test/Test_Batched_DenseUtils.hpp

@@ -309,6 +309,51 @@ void banded_to_full(InViewType& in, OutViewType& out, int k = 1) {
   Kokkos::deep_copy(out, h_out);
 }
 
+/// \brief Create a triangular matrix from an input matrix:
+/// Copies the input matrix into the upper/lower triangular of the output matrix specified
+/// by the parameter k. Zero out elements below/above the k-th diagonal.
+///
+/// \tparam InViewType: Input type for the matrix, needs to be a 3D view
+/// \tparam OutViewType: Output type for the matrix, needs to be a 3D view
+/// \tparam UploType: Type indicating whether the matrix is upper or lower triangular
+/// \tparam DiagType: Type indicating whether the matrix is unit or non-unit diagonal
+///
+/// \param in [in]: Input batched matrix, a rank 3 view
+/// \param out [out]: Output batched matrix, where the upper or lower
+/// triangular components are kept, a rank 3 view
+/// \param k [in]: The diagonal offset to be zero out (default is 0).
+///
+template <typename InViewType, typename OutViewType, typename UploType, typename DiagType>
+void create_triangular_matrix(InViewType& in, OutViewType& out, int k = 0) {
+  auto h_in   = Kokkos::create_mirror_view(in);
+  auto h_out  = Kokkos::create_mirror_view(out);
+  const int N = in.extent(0), BlkSize = in.extent(1);
+
+  Kokkos::deep_copy(h_in, in);
+  Kokkos::deep_copy(h_out, 0.0);
+  for (int i0 = 0; i0 < N; i0++) {
+    for (int i1 = 0; i1 < BlkSize; i1++) {
+      for (int i2 = 0; i2 < BlkSize; i2++) {
+        if constexpr (std::is_same_v<UploType, KokkosBatched::Uplo::Upper>) {
+          // Upper
+          // Zero out elements below the k-th diagonal
+          h_out(i0, i1, i2) = i2 < i1 + k ? 0.0 : h_in(i0, i1, i2);
+        } else {
+          // Lower
+          // Zero out elements above the k-th diagonal
+          h_out(i0, i1, i2) = i2 > i1 + k ? 0.0 : h_in(i0, i1, i2);
+        }
+      }
+
+      if constexpr (std::is_same_v<DiagType, KokkosBatched::Diag::Unit>) {
+        // Unit diagonal
+        h_out(i0, i1, i1) = 1.0;
+      }
+    }
+  }
+  Kokkos::deep_copy(out, h_out);
+}
+
 }  // namespace KokkosBatched
 
 #endif  // TEST_BATCHED_DENSE_HELPER_HPP