Generation of Positive Test Matrices with Known Positive Spectra Sufficient conditions are given for a real matrix to be similar to a positive matrix. This result is used to construct a similarity transformation which, when applied to a particular upper triangular matrix, yields a positive matrix with a preassigned positive spectrum. CACM August, 1968 Hall, C. A. Porsching, T. A. test matrices, positive matrices, similarity transformation, positive eigenvalues 5.1 5.14 CA680807 JB February 22, 1978 10:42 AM 1707 4 1707 1707 4 1707 1047 5 1707 1707 5 1707 1707 5 1707 1707 5 1707 1876 5 1707 2099 5 1707 511 5 1707 1662 6 1707 1707 6 1707 1707 6 1707