Gathering 2D Arrays in Fortran90, MPI_Gather - fortran

Question

I have problem with combining several 2D arrays into one big 2D array using MPI in Fortran.
I have equal size 2D arrays containing real numbers, every array is contained in different process:
numerical(subdsize,nt)
I want to combine them to one big array
numerical_final(nx,nt)
I am using the following command
CALL MPI_Gather(numerical(1:subdsize,nt),subdsize*nt,MPI_DOUBLE_PRECISION,numerical_final,subdsize*nt,MPI_DOUBLE_PRECISION,0, MPI_COMM_WORLD, mpierror)
Unfortunately the data that numerical_final array contains are a complete mess. I was looking for solutions really everywhere. I read this topic but it did not help me:
sending blocks of 2D array in C using MPI
I am using Intel Fortran 2018 compiler and Ubuntu 16.04.
Full code below.
I will be grateful for the help.
PROGRAM Advection
IMPLICIT NONE
INCLUDE 'mpif.h'
INTEGER :: nt,nx,i,steptime,tag,j
DOUBLE PRECISION :: R_dx, R_dt, R_c, R_cfl, R_t
DOUBLE PRECISION, DIMENSION(3) :: R_input
DOUBLE PRECISION, ALLOCATABLE, DIMENSION(:) :: xcoord
DOUBLE PRECISION, ALLOCATABLE, DIMENSION(:,:) :: numerical, numerical_final
DOUBLE PRECISION :: time_begin,time_end,time_elapsed
INTEGER:: myrank,nproc,mpierror,xdomains,subdsize
INTEGER:: status(MPI_STATUS_SIZE)
CALL MPI_Init(mpierror)
CALL MPI_Comm_size(MPI_COMM_WORLD,nproc,mpierror)
CALL MPI_Comm_rank(MPI_COMM_WORLD,myrank,mpierror)
IF (nproc<2) THEN
PRINT*, "Error, only more than 1"
CALL MPI_ABORT
END IF
IF (myrank .EQ. 0) THEN
OPEN(UNIT = 1, FILE = 'inputdata.dat')
READ(1,*) R_input(1)
READ(1,*) R_input(2)
READ(1,*) R_input(3)
READ(1,*) nx
CLOSE(1)
END IF
CALL MPI_Bcast(R_input, 3, MPI_DOUBLE_PRECISION, 0, MPI_COMM_WORLD, mpierror)
CALL MPI_Bcast(nx, 1, MPI_INTEGER, 0, MPI_COMM_WORLD, mpierror)
R_c=R_input(1)
R_cfl=R_input(2)
R_t=R_input(3)
R_dx=80./(nx-1)
nt=15
R_dt=R_t/(nt-1)
IF (myrank .EQ. 0) THEN
PRINT*, R_c*R_dt/R_dx
END IF
xdomains = nproc
IF ((MOD(nx,xdomains))==0) THEN
subdsize =nx/xdomains
ELSE
DO
nx=nx+1
IF ((MOD(nx,xdomains)) .EQ. 0) THEN
subdsize=nx/xdomains
EXIT
END IF
END DO
END IF
RAYS
ALLOCATE(xcoord(0:subdsize+1))
ALLOCATE(numerical(0:subdsize+1,nt))
DO i=0,subdsize+1
xcoord(i) = -40.-R_dx+i*R_dx+myrank*R_dx*subdsize
END DO
DO i = 0,subdsize+1
numerical(i,1)=0.5*(sign(1.,xcoord(i))+1.0)
END DO
IF (myrank .EQ. 0) THEN
DO i=1,nt
numerical(0:1,i)=0.
END DO
END IF
IF (myrank .EQ. nproc-1) THEN
DO i=1,nt
numerical(subdsize:subdsize+1,i)=1.
END DO
END IF
DO steptime=1, nt-1
tag = 1
IF (myrank .LT. nproc-1) THEN
CALL MPI_Send (numerical(subdsize,steptime),1,MPI_DOUBLE_PRECISION,myrank+1,tag,MPI_COMM_WORLD,mpierror)
END IF
IF (myrank .GT. 0) THEN
CALL MPI_Recv (numerical(0,steptime),1,MPI_DOUBLE_PRECISION,myrank-1,tag,MPI_COMM_WORLD,status,mpierror )
END IF
IF (myrank .EQ. 0) THEN
DO i = 2, subdsize+1
numerical(i,steptime+1)=numerical(i,steptime)-R_c*R_dt/R_dx*(numerical(i,steptime)-numerical(i-1,steptime))
END DO
ELSE
DO i = 1, subdsize+1
numerical(i,steptime+1)=numerical(i,steptime)-R_c*R_dt/R_dx*(numerical(i,steptime)-numerical(i-1,steptime))
END DO
END IF
END DO
ALLOCATE(numerical_final(nx,nt))
CALL MPI_Gather(numerical(1:subdsize,nt),subdsize*nt,MPI_DOUBLE_PRECISION,numerical_final,subdsize*nt,MPI_DOUBLE_PRECISION,0, MPI_COMM_WORLD, mpierror)
CALL MPI_Finalize(mpierror)
DEALLOCATE (numerical,numerical_final)
END PROGRAM
And inputfile
1.5 !c
0.5 !Courant
5.0 !time
100 !x points