Generation of Test Matrices Having Certain Sign Patterns and Prescribed Positive Spectra A class of orthogonal transformations is presented whose members transform a given positive diagonal matrix into a matrix having one of four special sign patterns. CACM July, 1969 Schneider, A. J. test matrices, positive matrices, sign patterns, orthogonal transformations, positive eigenvalues 5.1 5.14 CA690704 JB February 17, 1978 9:26 AM 1876 4 1876 2099 4 1876 1707 5 1876 1876 5 1876 1876 5 1876 1876 5 1876