DR 09-0144: SML, Formulas: Various functions, iterative search technique

[Shawn Villaron]

Here is my proposed response to this defect report:


¡¤         I agreed with almost all of the textual changes that Francis/BSI suggested, and have removed references to ¡°iterative search technique¡± from the standard.

¡¤         After experimenting with existing spreadsheets, we¡¯ll break backward compatibility of the IRR function if we change #NUM to #N/A as requested.  As such, I have not included that change in the list of textual changes below.

DR 09-0144 ¡ª SML, Formulas: Various functions, iterative search technique
Part 1, ¡ì18.17.7.28 will be updated as follows:

Syntax:

BETAINV  (  probability  ,  alpha  ,  beta  [  ,  [  A  ]  ,  [  B  ] ]  )
Description: Computes the inverse of the cumulative distribution function for a specified beta distribution. Given a value for probability, BETAINV is used to seek for the value x such that BETADIST(x, alpha, beta, A, B) = probability. Thus, precision of BETAINV depends on precision of BETADIST. BETAINV uses an iterative search technique.

Part 1, ¡ì18.17.7.37 will be updated as follows:

Return Type and Value: number ¨C The inverse of the one-tailed probability of the chi-squared distribution.
However, if

¡¤         probability < 0 or probability > 1, #NUM! is returned.

¡¤         degrees-freedom < 1 or degrees-freedom ¡Ý 1010, #NUM! is returned.

¡¤         An implementation uses an iterative search technique, and the search has not converged after some implementation-defined number of iterationsthe implementation determines that a return value cannot be computed, #N/A is returned
Part 1, ¡ì18.17.7.121 will be updated as follows:

Return Type and Value: number ¨C The inverse of the F probability distribution.
However, if

¡¤         probability < 0 or probability > 1, #NUM! is returned.

¡¤         degrees-freedom-1 < 1 or degrees-freedom-1 ¡Ý 1010, #NUM! is returned.

¡¤         degrees-freedom-2 < 1 or degrees-freedom-2 ¡Ý 1010, #NUM! is returned.

¡¤         An implementation uses an iterative search technique, and the search has not converged after some implementation-defined number of iterationsthe implementation determines that a return value cannot be computed, #N/A is returned
Part 1, ¡ì18.17.7.132 will be updated as follows:

Return Type and Value: number ¨C The inverse of the gamma distribution.
However, if

¡¤         probability < 0 or probability > 1, #NUM! is returned.

¡¤         alpha ¡Ü 0 or beta ¡Ü 0, #NUM! is returned.

¡¤         An implementation uses an iterative search technique, and the search has not converged after some implementation-defined number of iterationsthe implementation determines that a return value cannot be computed, #N/A is returned.
Part 1, ¡ì18.17.7.230 will be updated as follows:

Return Type and Value: number ¨C The inverse of the normal distribution for the specified mean and standard deviation.
However, if

¡¤         probability < 0 or if probability > 1, #NUM! is returned.

¡¤         standard-deviation ¡Ü 0, #NUM! is returned.

¡¤         An implementation uses an iterative search technique, and the search has not converged after some implementation-defined number of iterationsthe implementation determines that a return value cannot be computed, #N/A is returned.
Part 1, ¡ì18.17.7.232 will be updated as follows:

Return Type and Value: number ¨C The inverse of the standard normal distribution.
However, if

¡¤         probability < 0 or if probability > 1, #NUM! is returned.

¡¤         An implementation uses an iterative search technique, and the search has not converged after some implementation-defined number of iterationsthe implementation determines that a return value cannot be computed, #N/A is returned.
Part 1, ¡ì18.17.7.173 will be updated as follows:

Return Type and Value: number ¨C The internal rate of return for a series of cash flows.
However, if an implementation uses an iterative search technique, and the calculation has not converged after an implementation-defined number of iterations the implementation determines that a return value cannot be computed, #NUM! is returned.

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