Implement D3DXMatrixStack_Push

[H. Verbeet]

On 09/04/2008, Stefan Dösinger <stefan at codeweavers.com> wrote:
> You usually grow the memory by a factor of the old size because this reduces
>  the number of needed grows. So growing the stack is an O(log(n)) instead of
>  O(n), which is a huge difference.
>
No, the amortized time per push is O(1). The realloc becomes more
expensive as the array gets larger.

>  The drawback is that you have potentially more wasted memory. I don't know
>  what the theory says to that though. The amount of wasted memory is always
>  smaller than the amount of used memory at least if you double the size and
>  smaller if you grow it by 1/2 of the existing size, ...
>
On average the percentage of wasted memory is (factor - 1) / 2. You
make a trade of between memory usage and run time when picking the
factor.