A REDUCTION OF AN INDEFINITE SYMMETRIC MATRIX A TO THE FORM $LJL sup T$ BYROTATION AND DECOMPOSITIONS

Abstract

The paper discusses the reduction of a non-singular symmetric matrix $A$ by decomposition and similarity rotations to the form $LJL sup T$ where $L$ is a lower triangular matrix and $J$ is a diagonal matrix with diagonal elements plus or minus unity. In effect $PAP sup T~=~LJL sup T$, where $P$ is the product of plane rotations.