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Mathematica: Problems with integrating and plotting a function

  1. Feb 11, 2009 #1
    Hey, I have been trying to make Mathematica integrate the following function:

    [tex]r_{e}=\frac{c}{H_{0}}\int_{0}^{z}\frac{dz}{\left[\Omega_{NR}(1+z)^{3}+\Omega_n(1+z)^{3-n}+\Omega_{\Lambda}\right]^{\frac{1}{2}}}[/tex]

    There are two cases for which this equation needs to be integrated, seperately;

    (i) When [tex]\Omega_{\Lambda}=0[/tex]
    (ii) [tex]\Omega_n=0 [/tex]

    n is real, so is z and the sum of the density parameters is unity, thus if we take case (ii) [tex]\Omega_{\Lambda} = 1 - \Omega_{NR}[/tex]

    However Mathematica outputs the formatted version of the input line. Next I thought I would just define a function which includes the above integral, and then plot it for varying values of [tex]\Omega_{NR}[/tex] and n, however the problem is that often times the Kernel crashes or the curves plotted have gaps in them and/or end unexpectedly.

    I would of course prefer to have the integrated function as I presume it would save on plotting time as I need make plots for various values of n for case (i).

    Thanks
     
    Last edited: Feb 11, 2009
  2. jcsd
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