Hi!
Thanks for your reply. In my code node 0 is reading the input matrix from file and is distributing the columns to the corresponding nodes. The code is for LU decomposition and am not using the algorithm from any of the Linear alegbra libraries. I have written the code my self and i know it is not efficient .
My code is running fine for matrix sizes below 15000*15000. Iam not using dynamic memory allocation techniques in my code. Does this help me in running for higher matrix problem sizes.
To be honest i dont know what exactly a swap space mean.
Regards
Srinivasa Patri
Here is the code for your reference....
PROGRAM main
INCLUDE "mpif.h"
PARAMETER (N=16400)
COMPLEX*8 a(N,N)
INTEGER col(N)
INTEGER size,myrank
INTEGER i,j,k
INTEGER endcnt
INTEGER status(MPI_STATUS_SIZE),status1(MPI_STATUS_SIZE),ierr
DOUBLE PRECISION starttime,endtime
CALL MPI_INIT(ierr)
* Determining the size of the communication
CALL MPI_COMM_SIZE(MPI_COMM_WORLD, size, ierr)
* Determining the rank of each processor
CALL MPI_COMM_RANK(MPI_COMM_WORLD, myrank, ierr)
starttime = MPI_WTIME()
* Assigning columns to different processors
DO i = 1, N
col(i) = MOD(i-1, size)
ENDDO
* Open the matrix input file to read
OPEN (UNIT=1,FILE="matrix16834.data",STATUS='OLD')
* Reading the matrix data from input file
IF (myrank.EQ.0) THEN
DO j=1,N
DO i=1,N
READ (UNIT=1,FMT=*) a(i,j)
END DO
END DO
END IF
IF (myrank.EQ.0) THEN
DO i=1,N
IF (col(i).NE.0) THEN
CALL MPI_SEND(a(1,i),N,MPI_COMPLEX,col(i),50,
& MPI_COMM_WORLD,ierr)
END IF
END DO
ELSE
DO j=1,n
IF (col(j).EQ.myrank) THEN
CALL MPI_RECV(a(1,j),N,MPI_COMPLEX,0,50,
& MPI_COMM_WORLD,status,ierr)
END IF
END DO
END IF
DO k = 1,N-1
IF (col(k).EQ. myrank) THEN
DO i = k+1, N
a(i,k) = a(i,k) / a(k,k)
ENDDO
ENDIF
CALL MPI_BCAST(a(k,k), N-k+1, MPI_COMPLEX, col(k),
& MPI_COMM_WORLD, ierr)
DO j = k+1, N
IF (col(j).EQ. myrank) THEN
DO i = k+1, N
a(i,j) = a(i,j) - a(i,k) * a(k,j)
ENDDO
END IF
ENDDO
ENDDO
c------------------------------------------------------------------------------
DO i=1,N
IF (myrank.NE.0) THEN
IF (col(i).EQ.myrank) THEN
c WRITE (*,*) "PROCESSOR=",myrank,"COLUMN=",i
CALL MPI_SEND(a(1,i),N,MPI_COMPLEX,0,60,
& MPI_COMM_WORLD,ierr)
END IF
ELSE
IF (col(i).NE.0) THEN
CALL MPI_RECV(a(1,i),N,MPI_COMPLEX,col(i),
& 60,MPI_COMM_WORLD,status1,ierr)
c WRITE (*,*) "RECIEVING COLUMN=",i
END IF
END IF
END DO
C-------------------------------------------------------------------------------
IF (myrank.NE.0) THEN
CALL MPI_SEND(a(1,1),1,MPI_COMPLEX,0,52,
& MPI_COMM_WORLD,ierr)
ELSE
endcnt=1
DO WHILE(endcnt.LT.size)
CALL MPI_RECV(a(1,1),1,MPI_COMPLEX,
& MPI_ANY_SOURCE,MPI_ANY_TAG,MPI_COMM_WORLD,status,ierr)
IF (status(MPI_TAG).EQ.52) THEN
endcnt=endcnt+1
* WRITE(*,*)endcnt
END IF
END DO
OPEN(UNIT=11,FILE="lu_16834.data")
DO j=1,N
DO i=1,N
WRITE (UNIT=11,FMT=*) a(i,j)
END DO
END DO
END IF
endtime=MPI_WTIME();
WRITE (*,*) "Processor ",myrank," Time ",(endtime-starttime)/60,
& "minutes"
CALL MPI_FINALIZE(ierr)
END
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