isClose

immutable a = Matrix!(4, 4).fromRows([
    [1, 2, 3, 4],
    [5, 6, 7, 8],
    [9, 10, 11, 12],
    [13, 14, 15, 16],
]);

assert(a.isClose(a));

auto b = Matrix!(4, 4)();
b = a;
assert(a.isClose(b));
assert(b.isClose(a));

b[0, 0] = 100.0;
assert(!a.isClose(b));
assert(!b.isClose(a));

auto a = Matrix!(4, 4).fromRows([
    [1, 2, 3, 4],
    [5, 6, 7, 8],
    [9, 10, 11, 12],
    [13, 14, 15, 16],
]);

immutable expected = Matrix!(4, 4).fromRows([
    [9, 10, 11, 12],
    [5, 6, 7, 8],
    [1, 2, 3, 4],
    [13, 14, 15, 16],
]);

a.swapRows(0, 2);
assert(a.isClose(expected));

a.swapRows(3, 3);
assert(a.isClose(expected));