;ex1.pro:
;Procedure:   Shows an example of regression routine "ZREGR.PRO".
;             The original time series being modeled is cos(2i).
;             The regression model includes 6 harmonics, one of them
;             is cos(2.05i) which is close to the original time series.'
;             This procedure also plots (makes a postscript file) both
;             time series.
;To run:
;             Save this procedure as ex1.pro, get into IDL and then
;             type .r ex1.  You will need the IDL procedure ZREGR.PRO
;             in your current directory.

      IERROR=1
      N=20 & M=7
      T=fltarr(N) & F=fltarr(N,M)
      TMIN=-1.1 & TMAX=1.1
      for i=1,N do begin
        T(i-1)=cos(2.*i)  ; <== Original time series'
        F(i-1,0)=1.0
        F(i-1,1)=cos(2.05*i)
        F(i-1,2)=sin(0.4*i)
        F(i-1,3)=cos(0.6*i)
        F(i-1,4)=sin(0.8*i)
        F(i-1,5)=cos(0.3*i)
        F(i-1,6)=sin(0.9*i)
      endfor
      ZREGR,IERROR,N,M,T,TMIN,TMAX,F,WK,A,AINV,S,C,RESID,COV
      print,'i, T(i), T_model(i)'
      for i=0,N-1 do begin
        print, i, T(i), T(i)-RESID(i)
      endfor

      set_plot,'ps'
      device,/landscape
      !p.font=1
      !xtitle='Time series index'
      !ytitle='Time series value'
      !p.title='Original time series (solid) and model time series (dashed)'
      plot,T,thick=3,xthick=3,ythick=3,charsize=1.3,xcharsize=1.3,$
           ycharsize=1.3,/xs
      oplot,t-resid,linestyle=1,thick=6
      device,/close      

      end