ZI^ZJ Values of FI and FJ, respectively, the last time SUKFCE was 



called. (Not valid for MAX = 1.) 



FK Ciirvatiire of the wave ray at X^Y. 



Summary of Subroutine : 



For a specified A and X,Y position on the CMA.T grid, SUEFCE first determines 



I, J, XL, and YL. If MAX does not equal one, SUKFCE checks to see if ZI = 



FI and ZJ = FJ. If both equalities are true, the E values from the previous 



operation of SUEFCE are still valid, and the CXY and FK computations can be 



made directly. Otherwise, it is necessary to derive new E values, using C, 



FM, and S, before computing CXY and FK. 



Remarks : 



Program steps corresponding to SUEFCE20 through SUECE27 in the listing that 



follows were obtained from a program provided by Dr. W. C. Krumbein. (This 



program is described with the PRMAT program in Appendix C.) 



SUBROUTINE TITLE : MOVE. 



Variables Used in Subroutine : 



FKBAR Curvature used to obtain DELA for a given IT. 



FKKPP... FKBAR for IT = l8. 



FKKP ■ FKBAR for IT = n-1 where current FKBAR is for IT = n. (For 



IT = 1, FKKP equals the FKBAR used in determining XX and YY 



the previous time MOVE was called. ) 

 XX, YY, AA, 

 FKK X, Y, A, and FK values, respectively, for MAX = n + 1 where 



MAX = n when MOVE was called. 



DELX XX - X. 



DELY YY - Y. 



DELA AA - A. 



ABAR (A + AA)/2. 



44 



