Wikipedia:Reference desk/Archives/Mathematics/2007 December 21

= December 21 =

12 days of x-mas
How much money does the 'true love' spend (£) in 12 days of christmas? Lyrics--ジェイターナー ✉／✐ 12:28, 21 December 2007 (UTC)


 * I worked this out once years ago. I had to find out about the costs of slaves, and the rate of inflation between 1800s america and now.... it was quite a lot. mattbuck (talk) 12:35, 21 December 2007 (UTC)


 * Last year my maths teacher told me but I forgot it now so.... --ジェイターナー ✉／✐ 12:40, 21 December 2007 (UTC)


 * OK, let's start with a list:


 * 12 partridges and pear trees
 * 22 turtle doves
 * 30 french hens
 * 36 colly birds (crows, ravens, blackbirds...)
 * 40 gold rings
 * 42 Geese
 * 42 Swans
 * 40 Milkmaids
 * 36 female dancers
 * 30 Lords
 * 22 Pipers and pipes
 * 12 drummers and drums.
 * Do we want to assume that the people are hired? I think milkmaids would be employed at least... mattbuck (talk) 13:00, 21 December 2007 (UTC)


 * Or I suppose we could just look at the Christmas Price Index. mattbuck (talk) 13:04, 21 December 2007 (UTC)
 * Oh man. I can't believe such a perfect answer to this question already exists. Check out the video: http://www.pncchristmaspriceindex.com/ —Keenan Pepper 16:06, 21 December 2007 (UTC)


 * I’ve done a different analysis and found some interesting things. The true love prefers living beings to non-living objects (78%), animate beings to inanimate beings (96%), and of the humans, females to males (55%).  Assumptions: (a) each drum comes with 2 drumsticks, (b) no assumptions made for clothing and shoes.


 * Humans: There are 76 females, 30 males, and 34 pipers and drummers of unspecified gender but are traditionally more likely to be male than female. Thus, we have 64 males and 76 females – all stark naked. If we pair up the males and females as far as possible, that leaves 12 naked women with nothing to do but ... I’ll leave that to your imagination. (Shades of the 12 wise virgins!).  Merry Christmas, everyone.  :) --  JackofOz (talk) 23:13, 22 December 2007 (UTC)


 * Very vivid. --ジェイターナー ✉／✐ 19:15, 23 December 2007 (UTC)

Best CAS Software
What is the best free CAS software? Why? Smart_Viral(talk) 17:16, 21 December 2007 (UTC)


 * I don't have much experience, but I know there is this SAGE, which calls a whole bunch of other programs to perform operations. From its home page:
 * "SAGE includes interfaces to Magma, Maple, Mathematica, MATLAB, and MuPAD, and the free programs Axiom, GAP, GP/PARI, Macaulay2, Maxima, Octave, and Singular."
 * —Bromskloss (talk) 17:33, 21 December 2007 (UTC)


 * It also depends on the kind of computations you want to do, and why. If your main interest is, for example, Lie group computations, then the LiE computer algebra system is probably the best choice. Of the free systems to which SAGE interfaces Maxima does a lot of maths as long as your domain is confined to analysis and algebra on the real or complex fields. I have no experience with any of the other free systems. --Lambiam 22:49, 21 December 2007 (UTC)

Differentiation
This page says: 1) The left and right hand limits must agree. That is the limit to the left and to the right of the point must agree. - should that be changed to "must be equal" so that people can actually understand it? Why does it say agree in the first place? --Seans Potato Business 19:43, 21 December 2007 (UTC)
 * Wikibooks can be edited by anyone, so may well just be someone thought it sounded better that way. I do concur that it would be better if it said equal. mattbuck (talk) 20:02, 21 December 2007 (UTC)
 * [ec] "Agree" is a commonly used word in this context, though this sentence could be worked on a bit - changing the second occurence of "agree" to "be equal" can be a good start. -- Meni Rosenfeld (talk) 20:03, 21 December 2007 (UTC)
 * I would entirely agree with Meni on this one. A math-wiki (talk) 07:08, 22 December 2007 (UTC)
 * How are you approaching this, from the left or the right? --Lambiam 09:48, 22 December 2007 (UTC)
 * If we eliminate all wrong approaches, only the right way will be left. -- Meni Rosenfeld (talk) 11:26, 22 December 2007 (UTC)
 * You guys are so droll. —Keenan Pepper 22:30, 22 December 2007 (UTC)
 * That page is misleading by showing f inside all those limits. –Pomte 12:41, 22 December 2007 (UTC)
 * It was more than misleading, it was simply wrong. this was the offending edit. That page is in a pretty bad shape anyway; For starters, why in the first place is an introduction to limits in a page about differentiation? -- Meni Rosenfeld (talk) 12:54, 22 December 2007 (UTC)
 * I've removed it after realizing that it has no relevance to the original purpose of that section. –Pomte 13:06, 22 December 2007 (UTC)