Add sa test file

Author: ranjanan

test/sa_tests.jl

@@ -0,0 +1,58 @@
+import AMG: scale_cols_by_largest_entry!, strength_of_connection, 
+            SymmetricStrength, poisson
+function symmetric_soc(A::SparseMatrixCSC{T,V}, θ) where {T,V}
+    D = abs.(diag(A))
+    i,j,v = findnz(A)
+    mask = i .!= j
+    DD = D[i] .* D[j] 
+    mask = mask .& (abs.(v.^2) .>= (θ * θ * DD))
+
+    i = i[mask]
+    j = j[mask]
+    v = v[mask]
+
+    S = sparse(i,j,v, size(A)...) + spdiagm(D)
+
+    scale_cols_by_largest_entry!(S)
+
+    for i = 1:size(S.nzval,1)
+        S.nzval[i] = abs(S.nzval[i])
+    end
+
+    S
+end
+
+# Set up tests
+function test_symmetric_soc()
+
+    cases = generate_matrices()
+
+    for matrix in cases
+        for θ in (0.0, 0.1, 0.5, 1., 10.)
+            ref_matrix = symmetric_soc(matrix, θ)
+            calc_matrix = strength_of_connection(SymmetricStrength(θ), matrix)
+
+            @test sum(abs2, ref_matrix - calc_matrix) < 1e-6
+        end
+    end
+end
+
+function generate_matrices()
+    
+    cases = []
+
+    # Random matrices
+    srand(0)
+    for T in (Float32, Float64)
+        
+        for s in [2, 3, 5]
+            push!(cases, sprand(T, s, s, 1.))
+        end
+
+        for s in [2, 3, 5, 7, 10, 11, 19]
+            push!(cases, poisson(T, s))
+        end
+    end
+
+    cases
+end