*DECK DJAC SUBROUTINE DJAC (T, U, PD, NROWPD, RPAR, IPAR) C***BEGIN PROLOGUE DJAC C***SUBSIDIARY C***PURPOSE Evaluate Jacobian for DDEBDF quick check. C***LIBRARY SLATEC C***TYPE DOUBLE PRECISION (JAC-S, DJAC-D) C***AUTHOR Chow, Jeff (LANL) C***ROUTINES CALLED (NONE) C***REVISION HISTORY (YYMMDD) C 810801 DATE WRITTEN C 891214 Prologue converted to Version 4.0 format. (BAB) C 900415 Minor clean-up of prologue and code and name changed from C DDJAC to DJAC. (WRB) C***END PROLOGUE DJAC INTEGER IPAR, NROWPD DOUBLE PRECISION PD, R, R5, RPAR, RSQ, T, U, U1SQ, U2SQ, U1U2 DIMENSION U(*), PD(NROWPD,*), RPAR(*), IPAR(*) C***FIRST EXECUTABLE STATEMENT DJAC U1SQ = U(1)*U(1) U2SQ = U(2)*U(2) U1U2 = U(1)*U(2) RSQ = U1SQ + U2SQ R = SQRT(RSQ) R5 = RSQ*RSQ*R PD(3,1) = (3.D0*U1SQ - RSQ)/R5 PD(4,1) = 3.D0*U1U2/R5 PD(3,2) = PD(4,1) PD(4,2) = (3.D0*U2SQ - RSQ)/R5 PD(1,3) = 1.D0 PD(2,4) = 1.D0 RETURN END