Freeware 3D Math libraries

Anyone know of any math libraries compatible with OpenGL? Something like the D3DX helper library? I''ve spent about a month writing my own for quaternions/vectors/matrices etc. but some of the higher level functions like slerp and all of the matrix functions D3DX supports i cant find any source code for.

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~aussie "one of these days im going to cut you into little pieces!" - Pink Floyd