! $Id: runav.f90 2022-10-27 09:51:28Z ychen $

!****s* fsi/runav *
!
! NAME
!   runav  - This subroutine performs running averaging with sliding window
!
! SYNOPSIS
!    call runav(nw,x,y)
!
! DESCRIPTION
!    This subroutine performs running averaging with sliding window
!
! INPUTS
!    INTEGER,                   :: nw           window size for averaging (nw must be odd !!!)
!    REAL(wp), DIMENSION(:),    :: x            input array
!
! OUTPUT
!    REAL(wp), DIMENSION(:),    :: y   output array after smoothing
!
! AUTHOR
!   Yong Chen, NOAA/NESDIS/STAR, yong.chen@noaa.gov
!   Loknath Adhikari, UMD/CISESS, loknath.adhikari@noaa.gov
!
! COPYRIGHT
!   Copyright (c) 2022-2023 Yong Chen <yong.chen@noaa.gov>
!   For further details please refer to the file COPYRIGHT
!   which you should have received as part of this distribution.
!
!****

SUBROUTINE runav(nw,x,y)

      USE typesizes,         ONLY: wp => EightByteReal

      IMPLICIT none
      INTEGER,                  INTENT(inout) :: nw  ! window size for averaging (nw must be odd !!!)
      REAL(wp), DIMENSION(:),   INTENT(in)    :: x   ! input array
      REAL(wp), DIMENSION(:),   INTENT(inout) :: y   ! output array after smoothing

      INTEGER  :: nmax,  i, j, nw2

      nmax  = SIZE(x)

      DO i=1,nmax
	y(i) = x(i)
      ENDDO

      ! make sure nx is an odd number
      IF (mod(nw, 2) /= 1) THEN

        nw = nw - 1

      ENDIF

      nw2=(nw-1)/2

      DO i = nw2+1,nmax-nw2

	y(i)=0.0_wp

        DO j=-nw2,+nw2

          y(i)=y(i) + x(i+j)

        ENDDO

        y(i)=y(i)/nw

      ENDDO

END SUBROUTINE runav