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Re: Emacs Calc - Npr and NCR functions

From: Tassilo Horn
Subject: Re: Emacs Calc - Npr and NCR functions
Date: Wed, 20 Jul 2011 16:49:36 +0200
User-agent: Gnus/5.110018 (No Gnus v0.18) Emacs/24.0.50 (gnu/linux)

Peter Dyballa <address@hidden> writes:

Hi Peter,

>>> Does anyone know how to access the Npr and Ncr functions with Emacs
>>> calc?
>> What are those functions?
> Combinatorics, Binomial coefficients, permutations, combinations. Some
> desk or pocket calculators provide such functions.
> I think nPr is n!/(n-k)! and nCr is n!/k!(n-k)!...

Ok, so the functions and keys are:

,----[ (info "(calc)Combinatorial Functions") ]
|    The `k c' (`calc-choose') [`choose'] command computes the binomial
| coefficient `N'-choose-`M', where `M' is the number on the top of the
| stack and `N' is second-to-top.  If both arguments are integers, the
| result is an exact integer.  Otherwise, the result is a floating-point
| approximation.  The binomial coefficient is defined for all real
| numbers by `N! / M! (N-M)!'.

,----[ (info "(calc)Combinatorial Functions") ]
|    The `H k c' (`calc-perm') [`perm'] command computes the
| number-of-permutations function `N! / (N-M)!'.


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