TINV Formula Returns an Error in Excel 2003 (827743)

SYMPTOMS

When you use some inverse functions (CHIINV, FINV, GAMMAINV, LOGINV, TINV) in Microsoft Office Excel 2003, Excel 2003 will return an error value of #N/A for certain values that are calculated with no error in Microsoft Excel 2002.

CAUSE

To calculate inverse functions, TINV uses an iterative search technique. If the search does not converge after 100 iterations, the function returns the #N/A error value.

Excel 2002 did not have this behavior because it would incorrectly exit from these functions before hitting the maximum iteration depth.

MORE INFORMATION

Many inverse functions have been improved for Excel 2003 by continuing the search process to reach a higher level of refinement. Included in this set of inverse functions are: BETAINV, CHIINV, FINV, GAMMAINV, and TINV. No modifications were made to the respective functions that are called by these inverse functions: BETADIST, CHIDIST, FDIST, GAMMADIST, and TDIST. The only change that affected TINV was to redefine "acceptably close" in the search process to be much closer. The search now continues until the closest possible value of x is found (in the limits of Excel's finite precision arithmetic). The resulting x should have a TDIST(x, df, 2) value that differs from p by about 10^(-15).

For more information about TINV, click Microsoft Excel Help on the Help menu, type tinv in the Search for box in the Assistance pane, and then click Start searching to view the topic.

REFERENCES

For additional information about TINV , click the following article number to view the article in the Microsoft Knowledge Base:

828340 Excel Statistical Functions: TINV