DEFEHL(3)

SYNOPSIS
SUBROUTINE DEFEHL (F, NEQ, T, Y, H, YP, F1, F2, F3, F4, F5, YS, + RPAR, IPAR)

NAME
defehl - Subsidiary to DERKF

LIBRARY
SLATEC

TYPE
SINGLE PRECISION (DEFEHL-S, DFEHL-D)

AUTHOR
Watts, H. A., (SNLA)

DESCRIPTION
Fehlberg Fourth-Fifth order Runge-Kutta Method ********************************************************************** DEFEHL integrates a system of NEQ first order ordinary differential equations of the form dU/DX = F(X,U) over one step when the vector Y(*) of initial values for U(*) and the vector YP(*) of initial derivatives, satisfying YP = F(T,Y), are given at the starting point X=T. DEFEHL advances the solution over the fixed step H and returns the fifth order (sixth order accurate locally) solution approximation at T+H in the array YS(*). F1,---,F5 are arrays of dimension NEQ which are needed for internal storage. The formulas have been grouped to control loss of significance. DEFEHL should be called with an H not smaller than 13 units of roundoff in T so that the various independent arguments can be distinguished. This subroutine has been written with all variables and statement numbers entirely compatible with DERKFS. For greater efficiency, the call to DEFEHL can be replaced by the module beginning with line 222 and extending to the last line just before the return statement. **********************************************************************

SEE ALSO
DERKF

ROUTINES CALLED
(NONE)

REVISION HISTORY (YYMMDD)
800501 DATE WRITTEN
890831 Modified array declarations. (WRB)
891009 Removed unreferenced statement label. (WRB)
891214 Prologue converted to Version 4.0 format. (BAB)
900328 Added TYPE section. (WRB)
910722 Updated AUTHOR section. (ALS)