TREATISES on this subject have been somewhat numerous of late. We recently noticed in these columns an excellent, but fairly elementary work, “On Ordinary and Partial Differential Equations,” by Prof.

SIAM Journal on Applied Mathematics, Vol. 43, No. 6 (Dec., 1983), pp. 1259-1273 (15 pages) A constructive algorithm is developed to determine whether or not a given linear p.d.e. can be mapped into a ...

We study the solutions of ordinary linear differential equations whose coefficients are analytic elements. As one application we show nonexistence of index for certain linear differential operators ...