Spectral regression: a unified subspace learning framework for content-based image retrieval
LSQR: An Algorithm for Sparse Linear Equations and Sparse Least Squares
A global geometric framework for nonlinear dimensionality reduction.
Laplacian Eigenmaps and Spectral Techniques for Embedding and Clustering
Nonlinear dimensionality reduction by locally linear embedding.
Algorithm 583: LSQR: Sparse Linear Equations and Least Squares Problems