[RESOLVED] implementing SHA256, 512?

[solitario]

Hello all.
When I write the following:

echo sha1($variable_to_encode);

everything works fine.

But the same is not true when I replace "sha1" with "sha256" or "sha512".

I did a:

var_dump(hash_algos());

and I do have both listed on my system. Plus when I go to php.net/sha256, I don't get documentation the way you would with any other function.
If anyone could help me realize what I'm doing wrong I'd appreciate it.
Thanks.