WolframAlpha keeps calculating after it prints an answer

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BlackSails
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WolframAlpha keeps calculating after it prints an answer

Postby BlackSails » Tue Feb 23, 2010 6:38 am UTC

take the following: http://www.wolframalpha.com/input/?i=maximize+x^-x+between+.1+and+4

you can see wolfram alpha give you a first estimate, then correct it as it finds a better answer

raygungothic
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Re: WolframAlpha keeps calculating after it prints an answer

Postby raygungothic » Tue Feb 23, 2010 10:14 am UTC

I think it also caches queries in some way, though...

DavCrav
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Re: WolframAlpha keeps calculating after it prints an answer

Postby DavCrav » Mon Mar 01, 2010 9:44 am UTC

I've had this happen. It has a go at integration, gives some numerical answer, and then tries to give a nice expression for it afterwards. It's kind of cool.

mr-mitch
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Re: WolframAlpha keeps calculating after it prints an answer

Postby mr-mitch » Tue Mar 02, 2010 12:27 pm UTC

How long did it take for you? I've left it for a couple of minutes and I still have the approximate answer :(

edit: after 20 minutes, still no go.

Ended
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Re: WolframAlpha keeps calculating after it prints an answer

Postby Ended » Tue Mar 02, 2010 1:37 pm UTC

mr-mitch wrote:How long did it take for you? I've left it for a couple of minutes and I still have the approximate answer :(

For the x^-x one it doesn't give an exact answer, it just refines the approximate answer. It happens very quickly - reload the page and keep an eye on the last couple of digits in the answer for x. For me, they change from 97 to 79.
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joshz
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Re: WolframAlpha keeps calculating after it prints an answer

Postby joshz » Sun Mar 07, 2010 12:10 am UTC

It's likely using Newton's method to find a max. It first finds xn and then shows that to you, and then calculates xn+m and shows that to you instead (using n and m cause I have no idea how fast their machine can do this kind of thing.)
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