//             &&           +     mul
//           /   |         / \
//        !=    !=        mul -1
//       / |   /  |       / |
//    rem 0.0 cs1 sn1   -  cs2
//   / |           |   / |
// $0 cst         rem $0 rem
// cs1 == sign(cst)
// cs2 = 1 / cst i.e. the reciprocal
// Note that named operators like 'sn' and 'sn1' are different values produced by