Property	Value
Hex Value	`$24`
Categories	Catalog > F Math > Math
Localizations	FR: `fnInt(`

`fnInt(`

Overview

Returns the function integral of expression with respect to variable, between lower and upper, with specified tolerance.

Availability: Token available everywhere.

Syntax

fnInt(expression,variable,lower,upper[,tolerance])

Arguments

Name	Type	Optional
expression	expression
variable
lower
upper
tolerance		Yes

Location

math, MATH, 9:fnInt(

Description

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

Error Conditions

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.

Source: parts of this page were written by the following TI|BD contributors: DarkerLine, GoVegan, Myles_Zadok.

History

Calculator	OS Version	Description
TI-82	1.0	Added

Authors: Adrien Bertrand

fnInt(