Spline qualocation methods for variable-coefficient elliptic equations on curves

Summary.

Here the stability and convergence results of oqualocation methods providing additional orders of convergence are extended from the special class of pseudodifferential equations with constant coefficient symbols to general classical pseudodifferential equations of strongly and of oddly elliptic type. The analysis exploits localization in the form of frozen coefficients, pseudohomogeneous asymptotic symbol representation of classical pseudodifferential operators, a decisive commutator property of the qualocation projection and requires qualocation rules which provide sufficiently many additional degrees of precision for the numerical integration of smooth remainders. Numerical examples show the predicted high orders of convergence.