INTRODUCTION The documentation for the NASTRAN computer program consists of four manuals: the Theoretical Manual, the User's Manual, the Programmer's Manual Sample records for nastran theoretical manual The Block Lanczos algorithm was found to be extremely efficient, in particular, for very large size This edition covers the major numerical methods available in NX Nastran Version and in specific numerical modules are theoretically limited. The NX Nastran Theoretical Manual is a legacy document which we do not update. Lanczos, C., "An Iteration Method for the Solution of the Eigenvalue Lanczos , C. , " An Iteration Method for the Solution of the Eigenvalue froblem of Linear Differential and Integral Operators , " J. Res . Nat . Bur .