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Ti-89 Limit of Integral undefined BUT it is 4 both by hand and Mathematica

  1. Oct 21, 2014 #1
    I am giving the following input to Ti-89 Titanium:

    limit(S((2 x cos(100 x Pi x t)+2 x sin(10 x Pi x t))2 ,t,-t1,t1)/(2 x t1),t1,inf)

    where S is the integral symbol, Pi is π = 3.14, x is the multiplication symbol and inf is the infinity symbol

    The TI-89 answer is undef

    If I do it by hand it is 4 and Wolfram Mathematica with the following input agrees:

    Limit[Integrate[(2Sin[10Pit] + 2Cos[100Pit])2, t, -T, T}]/(2*T), T -> Infinity]

    Do you see any errors in my TI89 input?

    (I have made the same question in the Ti89 subreddit but it doesn't seem to be used by more than 5 people.)

    Thank you!

    Some more info:

    For the integral alone the Ti89 gives:

    -20 π T-10 sin(10 π T) cos(10 π T)+sin(100 π T) cos(100 π T))/((25 π)

    whereas mathematica gives:

    (400 π T - 10 Sin[20 π T] + Sin[200 π T])/(50 π) with the limit again 4 in Mathematica

    If I limit the Ti-89 result with mathematica, it returns -2/5
  2. jcsd
  3. Oct 26, 2014 #2
    Thanks for the post! Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
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