Some extensions of results of Titchmarsh on Dirac systems

Spectral properties are considered for a one-dimensional Dirac system with singularities at zero and infinity. Of primary concern is the asymptotic behavior of solutions near zero. From the form of these solutions, criteria are given for the singular point zero to be in the limit point or limit circle case. The Titchmarsh-Weyl m-coefficient at zero is shown to be meromorphic. This result, when combined with known behavior at infinity, is used to establish the location and class C/sup (1)/ nature of the essential spectrum