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62. GIVENS: Eigenvalues and Egienvectors by the
Givens Method
by Franklin Prosser, Department of Chemistry, Indiana University, Bloomington, Indiana 47405 Modified by Harvey Michels, United Aircraft Research Laboratories, and Franklin Prosser. Subroutine obtains the K lowest eigenvalues (and eigenvectors if requested) of a real symmetric matrix of order N. K may be 1 to N. Matrix must be stored by columns as a packed upper triangle. All vectors, including those for degenerate roots, will be orthonormal. This version is compatible with most FORTRAN IV dialects and is designed to run successfully on most computers, including machines with number range and word size inferior to the CDC 3600. FORTRAN IV (IBM 7090, CDC 3600, Univac 1108, etc.) Lines of Code: 458 Recommended Citation: H. Michels and F. Prosser, QCPE 11, 62 (1965). |