REAL X1, X2, DX, TOL

EXTERNAL F

X1 = -2.0

X2 = 2.0

DX = 0.125

TOL = 5.E-5

CALL SEARCH(X1, X2, DX, TOL, F)

END

SUBROUTINE SEARCH(XN, XX, DX, TOL, F)

REAL XN, XX, DX, TOL, X1, X2, SECANT

EXTERNAL F

X1 = XN

100 X2 = X1 + DX

IF (F(X1) * F(X2) .LT. 0.0) THEN

PRINT 1, SECANT(X1, X1+DX, TOL, F)

1 FORMAT(1X, 'A ROOT IS ', F8.5)

ENDIF

X1 = X2

IF (X1 .LT. XX) GOTO 100

END

REAL FUNCTION F(X)

REAL X

F = X*(X*X-3.0)+1.0

END