anchor.diff:  C   MODIFIED PBS AUG. 1971
   C   modified to increase number of layers to 50
   C***********************************************************************
  -      CHARACTER*6 TITLE,IDNT
  -      COMPLEX SAVE
  -      COMPLEX X, AX
  -C
  -      DIMENSION XR(8)
  -      DIMENSION X(300),AX(3,270),S(70),INV(70)
  -      COMMON /SOILA/ IDNT(6),BL(51),GL(51),FACT(51),H(51),R(51),BF(51)
  -      COMMON /EQ/ MFOLD,MA2,TITLE(5),DT, MA , MMA, DF,MX
  +      character*6 TITLE,IDNT
  +      complex SAVE
  +      complex X, AX
  +C
  +      dimension XR(8)
  +      dimension X(300),AX(3,270),S(70),INV(70)
  +      common /SOILA/ IDNT(6),BL(51),GL(51),FACT(51),H(51),R(51),BF(51)
  +      common /EQ/ MFOLD,MA2,TITLE(5),DT, MA , MMA, DF,MX
   C
         FREQ = 0.
         SFX = 0.
         SXX = 0.
   C   TRANSFORM VALUES IN X OR IN AX INTO THE TIME DOMAIN
  -      DO 24  I = 1,MFOLD
  -      IF (LS.EQ.0) GO TO 241
  +      do 24  I = 1,MFOLD
  +      if (LS.EQ.0) go to 241
         SAVE = X(I)
         X(I) = AX(LS,I)
         AX(LS,I) = SAVE
  
positive.code: C $NOFLOATCALLS
  C $NODEBUG
  C************************************
        SUBROUTINE AMP( N1,IN,INT,LL,LT,KPL,IDAMP,NA,DF)
  C * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
  C
  C   THIS ROUTINE COMPUTES THE AMPLIFICATION SPECTRUM BETWEEN ANY TWO
  
negative.code: C   MODIFIED OCT.  1971
  C
  C * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
        complex X, AX
        character*6 TITLE
  C
        dimension X( 68), AX(3, 64)
        common /EQ/ MFOLD,MA2,TITLE(5),DT, MA , MMA, DF,MX
  C
        F1 = .5/DT
        FR = FLOAT(IFR)
  