Microsoft KB Archive/827743

= TINV formula returns a #N/A error in Excel =

Article ID: 827743

Article Last Modified on 1/19/2007

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APPLIES TO


 * Microsoft Office Excel 2007
 * Microsoft Office Excel 2003

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SYMPTOMS
When you use some inverse functions (CHIINV, FINV, GAMMAINV, LOGINV, TINV) in Microsoft Office Excel 2003 and in later versions of Excel, Excel will return an error value of #N/A for certain values that are calculated.

Note In Microsoft Excel 2002, no error is returned.



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 and for later versions of Excel 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 &quot;acceptably close&quot; in the search process to be much closer. The search now continues until the closest possible value of x is found (within 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).

