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Command Summary

Approximately computes a definite integral.

Command Syntax


Menu Location


  1. Press MATH to access the Math menu.
  2. 9 to select fnInt(, or use arrows.

Calculator Compatibility


Token Size

1 byte

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(ln(X),X,0,1) <a difficult example>

Error Conditions

Related Commands