D does not use `char a[..]` as syntax for anything.

A pointer is declared as `char* p`, and an array as `char[] p`.

A two dimensional array parameter is declared as:

    void transpose(double[][] a);

Having to specify the dimensions as separate parameters is an unfortunate design choice:

1. It's clumsy to have to carry the dimensions around as separate items, rather than as one item

2. If the wrong X or Y is supplied, you have a massive memory corruption problem