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Origin fit plotted on mathematica

  1. Oct 30, 2011 #1
    Hi there. I have a problem with this. I'm trying to plot a polynomial fit done with origin 8.5 on mathematica. The thing is that the polynomial plot I get in mathematica from the coefficients given in originlab don't match, and I don't know why. I'll let you some pics of what I'm trying to do, the first one is the fit on origin lab, the second the tabs with the coefficients, and the third the plot on mathematica. I also draw two circles in the part of the graph which makes clear the differences between one plot and the other.

    What could be happening? is that the software isn't working or did I made any mistake when going from origin to mathematica?

    I tried to replace the exponential basis from 10 to e, but that makes it look even worse.

    Img. 1
    attachment.php?attachmentid=40487&stc=1&d=1319988012.png

    Img. 2
    attachment.php?attachmentid=40488&stc=1&d=1319988012.png

    Img. 3
    attachment.php?attachmentid=40489&stc=1&d=1319988012.png

    Bye there, and thank you in advance.
     

    Attached Files:

  2. jcsd
  3. Oct 30, 2011 #2
    This one is for the same range.
    attachment.php?attachmentid=40493&stc=1&d=1319992930.png
     

    Attached Files:

  4. Oct 31, 2011 #3
    Would you consider posting as plain ordinary ascii text the list of (x,y) pairs you gave Origin and the polynomial coefficients that Origin gave you back? Literally scrape the exact values off the screen or in some other way provide the numbers in text form.

    With plain ordinary ascii text anyone trying to reproduce the problem and offer a solution isn't required to type the whole thing back in, and even then can't even be sure they are using the exact same data.
     
  5. Nov 1, 2011 #4
    Hi Bill, thanks for posting. I'm sorry I couldn't answer you on yestarday. But here it is.

    Value
    B Intercept.....19,6
    B B1..............1,08687
    B B2..............-0,3755
    B B3..............0,05509
    B B4..............-0,00375
    B B5..............7,95435E-5
    B B6..............4,08596E-6
    B B7..............-2,86506E-7
    B B8..............6,43352E-9
    B B9..............-5,15102E-11

    I just copied it from the table that you can see in Img. 2. And here I give you the code I tiped into mathematica when plotting the polynomial:

    f[z_] := 19.6 + 1.08687*z - 0.3755 z^2 + 0.05509*z^3 - 0.00375*z^4 +
    7.95435 10^(-5)*z^5 + (4.08596 10^(-6))*z^6 - 2.86506 10^(-7)*z^7 +
    6.43352 10^(-9)*z^8 - 5.15102 10^(-11)*z^9
     
  6. Nov 1, 2011 #5
    I made the fit entirely with mathematica, and now it looks like the one given by origin. Perhaps the values origin gives in the table are truncated.
     
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