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MathGroup Archive 2007

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Re: Weird Print Result

  • To: mathgroup at
  • Subject: [mg74153] Re: Weird Print Result
  • From: Jens-Peer Kuska <kuska at>
  • Date: Mon, 12 Mar 2007 22:12:58 -0500 (EST)
  • Organization: Uni Leipzig
  • References: <et36rq$qgu$>
  • Reply-to: kuska at


the result of Print[] is Null -- this mean
that Print[] return nothing (but all functions
in Mathematica must return something) and so
it return Null, since X[[1]] is a sum, i.e. Head[X[[1]]]===Plus,
you replace every term in the sum by Null and you have


and this is 4*Null


Bruce Colletti wrote:
> Re Mathematica 5.2 under WinXP.
> The code below creates the correct output, except for a strange concluding "4 Null."
> What does this weird last line of output mean (list length?), why does it print, and how can it be suppressed?
> Thankx.
> Bruce
> n = 2;
> T = Array[p, {n, n}];
> X0 = Array[x, {n}];
> X = (Expand /@ (X0.MatrixPower[T, 2]));
> Print /@ X[[1]]

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