tag:blogger.com,1999:blog-5303307482158922565.post5072116429105912296..comments2024-03-22T13:39:55.941-07:00Comments on Math Mama Writes...: Wolfram Alpha Glitch!Sue VanHattumhttp://www.blogger.com/profile/10237941346154683902noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-5303307482158922565.post-57567167780203084202014-02-03T18:49:26.480-08:002014-02-03T18:49:26.480-08:00Yep, works fine for me too. Now. I'd love to h...Yep, works fine for me too. Now. I'd love to hear from them about the details behind this.Sue VanHattumhttps://www.blogger.com/profile/10237941346154683902noreply@blogger.comtag:blogger.com,1999:blog-5303307482158922565.post-66288832235372081442014-02-03T16:48:11.609-08:002014-02-03T16:48:11.609-08:00If I do quadratic (0,0), (1,1), (2,4)
it works fi...If I do quadratic (0,0), (1,1), (2,4)<br /><br />it works fine on WAKeithhttps://www.blogger.com/profile/08109858095787759082noreply@blogger.comtag:blogger.com,1999:blog-5303307482158922565.post-22743444581576925402014-01-18T12:06:28.927-08:002014-01-18T12:06:28.927-08:00Hi, Sue.
It is, indeed, puzzling, that Wolfram Al...Hi, Sue.<br /><br />It is, indeed, puzzling, that Wolfram Alpha (WA) wouldn't return the expected answer. WA is usually one of my first visits when I want to checks results of my calculations. (Getting results to 50 or more decimal places is nice, but not possible on a hand-held calculator.)<br />I also use translations of some LINPACK routines and ran your example through it: http://www.akiti.ca/LinLeastSqPoly4.html<br />I entered the following data pairs: (0,0),(1,1), (2,4) .<br />Made sure the check-box beside each pair was checked.<br />Selected the radio button under the "c" term to indicate a quadratic approximation.<br /><br />The program returned the correct approximation: y = 1*x^2<br />And no residuals, so we have a perfect fit.<br /><br />(Incidentally, I am a new user of the Desmos Graphing Calculator too; so far, I am very impressed with it.)<br /><br /> I am also a new user of the Desmos graphing calculator.David_Bhttps://www.blogger.com/profile/04006454809807494895noreply@blogger.comtag:blogger.com,1999:blog-5303307482158922565.post-4227743123074415252014-01-12T08:56:18.417-08:002014-01-12T08:56:18.417-08:00Thanks for the Reddit link, Patrick.
I was think...Thanks for the Reddit link, Patrick. <br /><br />I was thinking about what analytic mode might look like. Interpolation gives a curve that exactly goes through n points. If a polynomial is the best fit, it will be a polynomial of degree n-1 or lower. Seems to me that WA should use interpolation for best fit problems when the number of data points is less than the degree of the curve asked for, and could also check for close matches when the degree is higher.Sue VanHattumhttps://www.blogger.com/profile/10237941346154683902noreply@blogger.comtag:blogger.com,1999:blog-5303307482158922565.post-36926163128723830982014-01-12T05:08:16.511-08:002014-01-12T05:08:16.511-08:00It appears that this has to do with whether W|A is...It appears that this has to do with whether W|A is working analytically or numerically. I guess it processes this request and goes into <i>numeric</i> mode, and so gives approximations (which are essentially 0). On the other hand, if you ask for "polynomial interpolation of (0,0), (1,1), and (2,4)", it goes into <i>analytic</i> mode and gives the <a href="http://www.wolframalpha.com/input/?i=polynomial+interpolation+%280%2C0%29%2C+%281%2C1%29%2C+%282%2C4%29" rel="nofollow">exact answer</a>.<br /><br />I, too, found this interesting, and happened to see Peter Rowlett mention that he had posted this on Reddit, where some knowledgeable people responded. http://www.reddit.com/r/math/comments/1um6t7/can_wolfram_alpha_find_a_quadratic_passing/<br /><br />Patrick Honnerhttps://www.blogger.com/profile/04818663155751096756noreply@blogger.com