function x = test_sparse51 a = rand(200,100); b = rand(100,300); c = rand(200,100); d = rand(100,300); a(a>0.1) = 0; b(b>0.1) = 0; c(c>0.1) = 0; d(d>0.1) = 0; f = a + i*c; g = b + i*d; h = f*g; F = sparse(f); G = sparse(g); H = F*G; x = testeq(h,H);