Automatic nested dissection

Nested dissection is an ordering technique used to order the sparse symmetric positive definite systems of linear equations arising from discretizations to elliptic boundary value problems yielding regular n × n grids. By taking a recursive view of nested dissection we develop an ordering strategy which is particularly simple and efficient when n &equil; 2@−1. A FORTRAN IV subroutine of our algorithm is included and some experiments are presented.