A Rapid Procedure for Inverting Del-Square with Certain Computers

Abstract

A rapid procedure for inverting a second-order finite-difference form of the two-dimensional del-square operator is presented. The procedure may be used whenever the precision of the computer significantly exceeds the required accuracy of the results; effectively it acquires its speed by using the otherwise unneeded power of the computer represented by the additional precision. A particular variant should prove especially useful in numerical weather prediction, in instances when storage space is at a premium.