C---+----1----+----2----+----3----+----4----+----5----+----6----+----7--
      PROGRAM EX1
CProgram:   Shows an example of regression subroutine "ZREGR.F".
C           The original time series being modeled is cos(2i).
C           The regression model includes 6 harmonics, one of them
C           is cos(2.05i) which is close to the original time series.'
C           To run this program, you will need to compile it 
C           with the Fortran subroutine ZREGR.F.

      PARAMETER(IERROR=1,N=20,M=7,TMIN=-1.1,TMAX=1.1)
      REAL T(N),F(N,M),WK(N,2*N),A(M,M),AINV(M,M),S(M),C(M),
     & RESID(N),COV(M,M)

      DO i=1,N
        T(i)=cos(2.*i)  ! <== Original time series'
        F(i,1)=1.0
        F(i,2)=cos(2.05*i)
        F(i,3)=sin(0.4*i)
        F(i,4)=cos(0.6*i)
        F(i,5)=sin(0.8*i)
        F(i,6)=cos(0.3*i)
        F(i,7)=sin(0.9*i)
      ENDDO
      CALL ZREGR(IERROR,N,M,T,TMIN,TMAX,F,WK,A,AINV,S,C,RESID,COV)
      WRITE(*,*)'i, T(i), T_model(i)'
      DO i=1,N
        WRITE(*,*) i, T(i), T(i)-RESID(i)
      ENDDO

      STOP
      END