Tridiagonalization in atlas/ScaLapack/... with C.

[gazzel]

Hi.
Im veary new in atlas/ScaLapack, i wan't to tridiagonalize huge sparse symetric matics. I've done it with my own program using Lanczos algorithm ( dim. of matrix is about (2^24 x 2^24) so the algorithm has to deal without keeping matrix in mamory ), but now im loking sume routine for example in atlas which can do the same ( faster :) ) using sparse matrix ( i mean written in special form for example using 3-vedctors indexRow-( vector keeping number of non zero elem. in row),indexCol-(vector of column indices of non zero elem),data-vector of non zero elements itself :) . So is in Atlas/ScaLapack/...  such routine for C ?

regards