Separate HTML for Basic Foil 20 Node Program: Message Passing for Laplace Sover

Basic HTML version of Foils prepared 2 September 1997

Foil 20 Node Program: Message Passing for Laplace Sover

From CPS615 Laplace Example -- Programming Models and Performance CPS615 Basic Simulation Track for Computational Science -- Fall Semester 97. by Geoffrey C. Fox

DIMENSION PHINEW(NLOC+2), PHIOLD(NLOC+2)

Initialization NLOC=NTOT/NPROC (Assume NTOT divisible by NPROC)

I1=2
NLOC1=NLOC + 1
IF (PROCNUM.EQ.NPROC-1 .or. PROCNUM.EQ.0) NLOC1=NLOC1-1

BASIC LOOP

BEGIN TEST = 0

Shift to the right SOURCE = PHIOLD(NLOC1) address of data to be sent IF(PROCNUM.EQ.NPROC-1) SOURCE = "DUMMY" DEST = PHIOLD(1) address where data to be stored IF(PROCNUM.EQ.1)DEST = "DUMMY" CALL MPSHIFT(+1, SOURCE, DEST)

Shift to left SOURCE = FOLD(I1) IF(PROCNUM.EQ.0) SOURCE = "DUMMY" address of data to be sent DEST = PHIOLD(NLOC1+1) IF(PROCNUM.EQ.NPROC-1) DEST = "DUMMY" address where data to be stored CALL MPSHIFT(-1, SOURCE, DEST)

DO 1 I=I1,NLOC1 TEMP = 0.5 * (PHIOLD(I-1) + PHIOLD(I+1)) TEST = AMAX1(TEST,ABS(TEMP-PHIOLD(I))) 1 PHINEW (I) = TEMP DO 2 I=I1, NLOC1 2 PHIOLD(I) = PHINEW(I)
CALL GLOBALMAX (TEST) IF (TEST>CONVG) GO TO BEGIN ELSE STOP