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.
