Currently the contents of Stride depend on from which end we look at it: auto m = [1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4]; // 3 rows, 4 columns auto col = stride(m, 4); assert(equal(col, [1, 1, 1])); assert(equal(retro(col), [4, 4, 4])); Is the quantum behavior intended? -- Tomek