fnInt(f(var),var,a,b[,tol]) computes an approximation to the definite integral of f with respect to var from a to b. tol controls the accuracy of the integral computed. The default value of tol is 10-5. fnInt( returns exact results for functions that are polynomials of small degree.
fnInt( only works for real numbers and expressions. The Gauss-Kronrod method is used for approximating the integral.
Tip: Sometimes, to get an answer of acceptable accuracy out of fnInt(, substitution of variables and analytic manipulation may be needed.
fnInt(1/X,X,1,2) .6931471806 fnInt(ln(X),X,0,1) <a difficult example> -.999998347 fnInt(ln(X),X,0,1,e-11) -1
- ERR:DOMAIN is thrown if tol is 0.
- ERR:ILLEGAL NEST is thrown if fnInt( occurs in the expression to be integrated.
- ERR:TOL NOT MET may occur if the tolerance is too small.