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!Environment Canada - Atmospheric Science and Technology License/Disclaimer,
!                     version 3; Last Modified: May 7, 2008.
!This is free but copyrighted software; you can use/redistribute/modify it under the terms
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!

      subroutine calchev 1,4
      use mod4dv, only : l4dvar
#if defined (DOC)
*
***s/r minimize  - Compute Hessian Eigen-Vectors - Only call SUPRECON if NPRECON > 0
*
*
*Author  : M. Buehner *ARMA/MSC July, 2002
*Revision:
*
*Arguments
*    -NONE-
#endif
      IMPLICIT NONE
*implicits
#include "comdim.cdk"
#include "comlun.cdk"
#include "comcva.cdk"
#include "comanl.cdk"
*
      INTEGER IERR,ILEN
c
      call printrev("SUBROUTINE calchev:",1)
c
c Calculate Hessian Eigenvectors
c
      WRITE(NULOUT,*) 'IN CALCHEV: NPRECON=',nprecon
      IF(NPRECON.ge.1) THEN
c
        NCV=3*NPRECON
        NCORDIM=NVADIM
        ILEN = NCORDIM*NCV
        CALL HPALLOC(PTRRNK1,MAX(ILEN,1),IERR,8)
        ILEN = NCORDIM*NPRECON
        CALL HPALLOC(PTRRNK2,MAX(ILEN,1),IERR,8)
        ILEN = NPRECON
        CALL HPALLOC(PTHESEVAL,MAX(ILEN,1),IERR,8)
c
        WRITE(NULOUT,*) '**************************************'
        WRITE(NULOUT,*) '***SETTING UP HESSIAN EIGEN VECTORS***'
        WRITE(NULOUT,*) '**************************************'
c calculate 3Dvar or 4Dvar Hessian
        CALL SUPRECON
      ELSE
        WRITE(NULOUT,*) 'NPRECON not a positive number - Nothing done!'
      ENDIF
c
      if(l4dvar) call endsim
C
      RETURN
      END