PROGRAM D9R7
C	Driver for routine ZBRENT
	EXTERNAL BESSJ0
	PARAMETER(N=100,NBMAX=20,X1=1.0,X2=50.0)
	DIMENSION XB1(NBMAX),XB2(NBMAX)
	NB=NBMAX
	CALL ZBRAK(BESSJ0,X1,X2,N,XB1,XB2,NB)
	WRITE(*,'(/1X,A)') 'Roots of BESSJ0:'
	WRITE(*,'(/1X,T19,A,T31,A/)') 'x','F(x)'
	DO 11 I=1,NB
		TOL=(1.0E-6)*(XB1(I)+XB2(I))/2.0
		ROOT=ZBRENT(BESSJ0,XB1(I),XB2(I),TOL)
		WRITE(*,'(1X,A,I2,2X,F12.6,E16.4)') 'Root ',I,ROOT,BESSJ0(ROOT)
11	CONTINUE
	END