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Subject: GAMMADIST function's mathematical formula
Hi, I just got a heads-up from an OOo code contributor working on functions that our mathematical formula of GAMMADIST is different from what Calc and Excel implemented. Our definition says GAMMADIST(x;α;λ;FALSE()) = λ^α / Γ(α) * x^(α-1) * e^(-λ*x) Implementation in Calc and Excel is GAMMADIST(x;a;b;FALSE()) = 1 / (b^a * Γ(a) ) * x^(a-1) * e^(-x/b) See also the ECMA/MOOXML draft. The difference seems to result from literature where both definitions can be encountered, with λ=1/b. However, results are slightly different, e.g. Implementation GAMMADIST(2;3;5;FALSE()) returns ≈0.010725 whereas our definition GAMMADIST(2;3;5;FALSE()) would return ≈0.01134998 I propose to change our definition to reflect reality of common implementation. Eike -- Automatic string conversions considered dangerous. They are the GOTO statements of spreadsheets. --Robert Weir on the OpenDocument formula subcommittee's list.
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