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	SUBROUTINE ITER8(I,K,X,XM1,Y,YM1,YREF,DX,ID,TOL)
	ER=Y-YREF
	IF(K.GT.29) GO TO 4
	K=K+1
	IF(K.EQ.2) GO TO 2
	IF(ABS(ER).LT.TOL) GO TO 3
	DY=Y-YM1
	IF(ABS(DY).LT..1E-10) GO TO 6
C------2ND OR GREATER CYCLE
	DX=(XM1-X)*ER/DY
	YM1=Y
	XM1=X
	RETURN
C------EXIT IF THE FUNCTION HAS NOT CHANGED
6	TB=10.*TOL
	IF(ABS(ER).LE. TB) GO TO 3
	WRITE(5,7) I,X,XM1,Y,YM1,ER
7	FORMAT(' NO CHANGE IN THE ',I2,'TH LOOP',/,5(2X,E12.5))
	ID=-1
	RETURN
C------EXIT IF NOT CONVERGED AFTER 30 CYCLES
4	WRITE(5,5) I,X,XM1,Y,YM1,ER
5	FORMAT(' LONG ',I2,'TH LOOP',/,5(2X,E12.5))
C------NORMAL EXIT
3	ID=1
	RETURN
C------FIRST CYCLE
2	YM1=Y
	XM1=X
	DX=-X*ER/(8.*ABS(Y))
	RETURN
	END