diff --git a/m_compact.f90 b/m_compact.f90
index eb98435..4d7cfe6 100644
--- a/m_compact.f90
+++ b/m_compact.f90
@@ -330,7 +330,7 @@
      END SUBROUTINE ptdslv
 
      SUBROUTINE par_ptdslv(r,la,wa,nd,n,nall)
-      INTEGER,PARAMETER :: nb = 128
+      INTEGER,PARAMETER :: nb = 64
       INTEGER,INTENT(IN) :: n,nd,nall
       REAL*8,INTENT(INOUT),DIMENSION(nd,n) :: r
       REAL*8,INTENT(IN),DIMENSION(nall) :: la,wa
@@ -380,7 +380,7 @@
 
               buf(:,1) = r(jj:jj+nb-1,n)
               buf(:,2) = sum(jj:jj+nb-1)
-              CALL MPI_SSEND(buf, 2*nb, MPI_REAL8, pid+1, 1, MPI_COMM_TASK, mpi_err)
+              CALL MPI_SEND(buf, 2*nb, MPI_REAL8, pid+1, 1, MPI_COMM_TASK, mpi_err)
 
           ENDDO
 
@@ -446,7 +446,7 @@
 
               buf(:,1) = r(jj:jj+nb-1,1)
               buf(:,2) = r(jj:jj+nb-1,n)
-              CALL MPI_SSEND(buf, 2*nb, MPI_REAL8, pid-1, 2, MPI_COMM_TASK, mpi_err)
+              CALL MPI_SEND(buf, 2*nb, MPI_REAL8, pid-1, 2, MPI_COMM_TASK, mpi_err)
 
           ENDDO
 
@@ -476,7 +476,7 @@
 
               buf(:,1) = r(jj:jj+nb-1,n)
               buf(:,2) = sum(jj:jj+nb-1)
-              CALL MPI_SSEND(buf, 2*nb, MPI_REAL8, pid+1, 1, MPI_COMM_TASK, mpi_err)
+              CALL MPI_SEND(buf, 2*nb, MPI_REAL8, pid+1, 1, MPI_COMM_TASK, mpi_err)
 
           ENDDO
 
@@ -498,7 +498,7 @@
 
               buf(:,1) = r(jj:jj+nb-1,1)
               !buf(:,2) = r1
-              CALL MPI_SSEND(buf, 2*nb, MPI_REAL8, pid-1, 2, MPI_COMM_TASK, mpi_err)
+              CALL MPI_SEND(buf, 2*nb, MPI_REAL8, pid-1, 2, MPI_COMM_TASK, mpi_err)
 
           ENDDO