test cases and NEWS for #30372 (sparse matmul) (#30433)

NEWS.md

@@ -33,6 +33,10 @@ Standard library changes
 
 * Added keyword arguments `rtol`, `atol` to `pinv` and `nullspace` ([#29998]).
 
+#### SparseArrays
+
+* performance improvements for sparse matrix-matrix multiplication ([#30372]).
+
 #### Dates
 
 * Fixed `repr` such that it displays `DateTime` as it would be entered in Julia ([#30200]).

stdlib/SparseArrays/test/sparse.jl

@@ -318,12 +318,22 @@ end
 end
 
 @testset "matrix multiplication" begin
-    for i = 1:5
-        a = sprand(10, 5, 0.7)
-        b = sprand(5, 15, 0.3)
-        @test maximum(abs.(a*b - Array(a)*Array(b))) < 100*eps()
-        @test maximum(abs.(SparseArrays.spmatmul(a,b) - Array(a)*Array(b))) < 100*eps()
-        f = Diagonal(rand(5))
+    for (m, p, n, q, k) in (
+                            (10, 0.7, 5, 0.3, 15),
+                            (100, 0.01, 100, 0.01, 20),
+                            (100, 0.1, 100, 0.2, 100),
+                           )
+        a = sprand(m, n, p)
+        b = sprand(n, k, q)
+        as = sparse(a')
+        bs = sparse(b')
+        ab = a * b
+        aab = Array(a) * Array(b)
+        @test maximum(abs.(ab - aab)) < 100*eps()
+        @test a*bs' == ab
+        @test as'*b == ab
+        @test as'*bs' == ab
+        f = Diagonal(rand(n))
         @test Array(a*f) == Array(a)*f
         @test Array(f*b) == f*Array(b)
     end