*DECK PRODP SUBROUTINE PRODP (ND, BD, NM1, BM1, NM2, BM2, NA, AA, X, Y, M, A, + B, C, D, U, W) C***BEGIN PROLOGUE PRODP C***SUBSIDIARY C***PURPOSE Subsidiary to BLKTRI C***LIBRARY SLATEC C***TYPE SINGLE PRECISION (PRODP-S, PROCP-C) C***AUTHOR (UNKNOWN) C***DESCRIPTION C C PRODP applies a sequence of matrix operations to the vector X and C stores the result in Y (periodic boundary conditions). C C BD,BM1,BM2 are arrays containing roots of certain B polynomials. C ND,NM1,NM2 are the lengths of the arrays BD,BM1,BM2 respectively. C AA Array containing scalar multipliers of the vector X. C NA is the length of the array AA. C X,Y The matrix operations are applied to X and the result is Y. C A,B,C are arrays which contain the tridiagonal matrix. C M is the order of the matrix. C D,W,U are working arrays. C IS determines whether or not a change in sign is made. C C***SEE ALSO BLKTRI C***ROUTINES CALLED (NONE) C***REVISION HISTORY (YYMMDD) C 801001 DATE WRITTEN C 891214 Prologue converted to Version 4.0 format. (BAB) C 900402 Added TYPE section. (WRB) C***END PROLOGUE PRODP