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Mathetica function (help fix my equation please)

  1. Mar 15, 2016 #1
    Hi guys,

    I have a problem with Mathematica. The equation (see attachment) is SUPPOSE TO give:
    n[0]=n0
    n[1]=x0-n0
    n[2]=x1-x0+n0
    n[3]=x2-x1+x0-n0
    n[4]=x3-x2+x1-x0+n0
    n[5]=x4-x3+x2-x1+x0-n0
    n[6]=x5-x4+x3-x2+x1-x0+n0-1
    ...

    But when I put in n[1] I get the following errors and output:

    Sum::itraw: Raw object 1 cannot be used as an iterator. >>
    Sum::vloc: The variable 1 cannot be localized so that it can be assigned to numerical values. >>
    Sum::itraw: Raw object 1 cannot be used as an iterator. >>
    Sum::vloc: The variable 1 cannot be localized so that it can be assigned to numerical values. >>
    [tex]\sum _{1=1}^1 (-1)^{1-1} x_{1-1}-n_0[/tex]

    What do I need to change to give me an output of [tex] x_ 0 + n_ 0 [/tex]


    n[2] gives:
    [tex] \sum _{2=1}^2 (-1)^2 x_{2-1}+n_0 [/tex]
    when I want it to give me: [tex] x_1-x_0-n_0[/tex]
     

    Attached Files:

    • 1.jpg
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    Last edited: Mar 15, 2016
  2. jcsd
  3. Mar 15, 2016 #2

    jedishrfu

    Staff: Mentor

  4. Mar 15, 2016 #3
    I been playing around with the LATEX thing.. using Mathematica's right click and "copy as Latex" function.
    I have attached a copy of my original equation, below is an attempt to convert it into Latex.

    [tex] \sum _{z=1}^z (-1)^z x_{z-1}-\sum _{z=6}^z 1+n_0 (-1)^z [/tex]

    There seems to be a problem with "Reals" and "Absolutes" How do I do these in Latex?
     

    Attached Files:

    • 1.jpg
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      File size:
      7.6 KB
      Views:
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    Last edited: Mar 15, 2016
  5. Mar 15, 2016 #4

    Dale

    Staff: Mentor

    The problem is your summation.
    [tex] \sum _{z=1}^z f(z) [/tex] is bad input. It should be something like
    [tex] \sum _{i=1}^z f(i) [/tex]
     
  6. Mar 15, 2016 #5
    Yep, you're right! I've got it working perfectly now!

    My other question is: How do I write the ABS and REALS in LATEX? (so I can post things on physics forms better)

    so far i've got:

    [tex] \sum _{j=1}^z (-1)^j x_{j-1}-\sum _{j=6}^z 1+n_0 (-1)^z [/tex]
     

    Attached Files:

    • 2.jpg
      2.jpg
      File size:
      7.4 KB
      Views:
      51
  7. Mar 15, 2016 #6

    Dale

    Staff: Mentor

    When I am trying to troubleshoot I would rather just have the straight code. The fancy formatting is nice, but makes finding code errors more difficult. I know that isn't everyone's preference, but it is my preference. I would just use the "code" tag and copy and paste the Mathematica input.
     
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