PROGRAM    LIGHT_CURVE
      IMPLICIT   NONE 
      INTEGER*4  MP
      PARAMETER  ( MP = 128 )
      CHARACTER  FILIN*128, BUF(MP)*256, COMP*1, BAND*1, DATE_STR*19
      INTEGER*4  J1, J2, J3, KP, NP, MJD, MJD_0, IUER
      REAL*8     TIM(MP), VAL(MP), ERR(MP), SEC, FLUX_A, FLUX_B, &
     &           FLUX_A_ERR, FLUX_B_ERR, FLUX_ERR_SYS, FA(MP), FB(MP), PC
      REAL*8,    EXTERNAL :: PEARSON_CORR
!
      COMP = 'B'
      BAND = 'X'
      FLUX_ERR_SYS = 0.05
!
! L: 770 700 270 K
!
      FILIN = '/astrogeo/4C+35.28/4C+35.28_properties.txt'
      IUER = -1
      CALL RD_TEXT ( FILIN, MP, BUF, NP, IUER )
      IF ( IUER .NE. 0 ) CALL EXIT ( 1  )
!
      DATE_STR = '1990.01.01_00:00:00'
      CALL DATE_TO_TIME ( DATE_STR, MJD_0, SEC, IUER )
      KP = 0
      DO 410 J1=1,NP
         IF ( BUF(J1)(46:46) == BAND ) THEN
              DATE_STR = BUF(J1)(11:14)//'.'//BUF(J1)(15:16)//'.'//BUF(J1)(17:18)//'_00:00:00'
              CALL DATE_TO_TIME ( DATE_STR, MJD, SEC, IUER )
              KP = KP + 1
              TIM(KP) = 1990 + (MJD - MJD_0)/365.25D0
              READ ( UNIT=BUF(J1)(81:86),   FMT='(F6.4)' ) FLUX_A
              READ ( UNIT=BUF(J1)(116:121), FMT='(F6.4)' ) FLUX_B
              READ ( UNIT=BUF(J1)(126:130), FMT='(F6.4)' ) FLUX_B_ERR
              IF ( COMP == 'A' ) THEN
                   VAL(KP) = FLUX_A
                   ERR(KP) = FLUX_A * 0.05
                 ELSE IF ( COMP == 'B' ) THEN
                   VAL(KP) = FLUX_B
                   ERR(KP) = FLUX_B_ERR
                 ELSE IF ( COMP == 'R' ) THEN
                   VAL(KP) = FLUX_B/FLUX_A
                   ERR(KP) = FLUX_B_ERR/FLUX_A
              END IF
              FA(KP) = FLUX_A
              FB(KP) = FLUX_B
         END IF
 410  CONTINUE 
      IUER = -1
      IF ( KP > 0 ) THEN
           CALL DIAGI_SETDEF ( IUER, 'DIAGI_ILST', 2 )
           CALL DIAGI_SETDEF ( IUER, 'DIAGI_IBST', 2 )
           CALL DIAGI_SETDEF ( IUER, 'DIAGI_IPST', 5 )
           CALL DIAGI_1E ( KP, TIM, VAL, ERR, IUER )
           PC = PEARSON_CORR ( KP, FA, FB )
           WRITE ( 6, 110 ) PC
 110       FORMAT ( 'Correlation coefficient: ' , F6.3 )
           CALL DIAGI_2  ( KP, TIM, FA, KP, TIM, 20.0D0*FB, IUER )
      END IF
      END  PROGRAM    LIGHT_CURVE  !#!  
!
! ------------------------------------------------------------------------
!
      FUNCTION   PEARSON_CORR ( N, FA, FB )
      IMPLICIT   NONE 
      INTEGER*4  N
      REAL*8     FA(N), FB(N)
      REAL*8     PEARSON_CORR
      REAL*8     FA_MEAN, FB_MEAN, FAFA, FAFB, FBFB
      INTEGER*4  J1, J2
!
      FA_MEAN = 0.0D0
      FB_MEAN = 0.0D0
      DO 410 J1=1,N
         FA_MEAN = FA_MEAN + FA(J1)
         FB_MEAN = FB_MEAN + FB(J1)
 410  CONTINUE 
      FA_MEAN = FA_MEAN/N
      FB_MEAN = FB_MEAN/N
!
      FAFA = 0.0D0
      FBFB = 0.0D0
      FAFB = 0.0D0
      DO 420 J2=1,N
         FAFA = FAFA + (FA(J2) - FA_MEAN)**2
         FBFB = FBFB + (FB(J2) - FB_MEAN)**2
         FAFB = FAFB + (FA(J2) - FA_MEAN)*(FB(J2) - FB_MEAN)
 420  CONTINUE 
!
      PEARSON_CORR = FAFB/DSQRT ( FAFA*FBFB ) 
!
      RETURN
      END  FUNCTION  PEARSON_CORR  !#!