1*DECK DFDEQC 2 SUBROUTINE DFDEQC (T, U, UPRIME, RPAR, IPAR) 3C***BEGIN PROLOGUE DFDEQC 4C***SUBSIDIARY 5C***PURPOSE Derivative evaluator for DDEPAC quick checks. 6C***LIBRARY SLATEC 7C***TYPE DOUBLE PRECISION (FDEQC-S, DFDEQC-D) 8C***AUTHOR Chow, Jeff, (LANL) 9C***ROUTINES CALLED (NONE) 10C***REVISION HISTORY (YYMMDD) 11C 810801 DATE WRITTEN 12C 891214 Prologue converted to Version 4.0 format. (BAB) 13C 900415 Name changed from DDF to DFDEQC. (WRB) 14C***END PROLOGUE DFDEQC 15C 16C Declare arguments. 17C 18 INTEGER IPAR(*) 19 DOUBLE PRECISION RPAR(*), T, U(*), UPRIME(*) 20C 21C Declare local variables. 22C 23 DOUBLE PRECISION R, RSQ, R3 24C***FIRST EXECUTABLE STATEMENT DFDEQC 25 RSQ = U(1)*U(1) + U(2)*U(2) 26 R = SQRT(RSQ) 27 R3 = RSQ*R 28 UPRIME(1) = U(3) 29 UPRIME(2) = U(4) 30 UPRIME(3) = -(U(1)/R3) 31 UPRIME(4) = -(U(2)/R3) 32 RETURN 33 END 34