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Re: Re: Why is Mathematica assuming k==l and how do I

  • To: mathgroup at smc.vnet.net
  • Subject: [mg92699] Re: [mg92684] Re: Why is Mathematica assuming k==l and how do I
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Sat, 11 Oct 2008 06:41:34 -0400 (EDT)
  • Reply-to: hanlonr at cox.net

Look in the documentation for the command Part


Bob Hanlon

---- mariam <mariamsaleh.khan at gmail.com> wrote: 

=============
On Oct 8, 12:38 pm, Bob Hanlon <hanl... at cox.net> wrote:
> Integrate[Cos[k alpha] Cos[l alpha], {alpha, -Pi, Pi},
>  Assumptions -> {l == k, Element[{l, k}, Integers]}]
>
> Pi
>
> Integrate[Cos[k alpha] Cos[l alpha], {alpha, -Pi, Pi},
>  Assumptions -> {l != k, Element[{l, k}, Integers]}]
>
> 0
>
> Assuming[{l == k, Element[{k, l}, Integers]},
>  Integrate[Cos[k alpha] Cos[l alpha], {alpha, -Pi, Pi}]]
>
> Pi
>
> Assuming[{l != k, Element[{k, l}, Integers]},
>  Integrate[Cos[k alpha] Cos[l alpha], {alpha, -Pi, Pi}]]
>
> 0
>
> Bob Hanlon
>
> ---- Aaron Fude <aaronf... at gmail.com> wrote:
>
> =============
> As in
>
> Assuming[Element[{k, l}, Integers] ,
>  Integrate[Cos[k alpha] Cos[l alpha], {alpha, -Pi, Pi}]]
>
> I get 0 whereas the answer is Pi if k=l;
>
> Thanks!
>
> Aaron
>
> --
>
> Bob Hanlon


hi all,
i found your group via web-search.
i am new to mathematica and learning about some codes needed in my
projects.
i want to know that:
1)

Do[{
  	amplist[i1]= Read[StringJoin[jproc,"/",QCD[i1],"diagrams.amp"]],
  	ileng[i1] = Length[amplist[i1]],

	Do[{
    	Print["Processing amp[",i1,",",i2,"]"],
    	If[i1===2,{amp[i1,i2] = amplist[i1][[i2]][[3]]}, {amp[i1,i2] =
amplist[i1][[i2]][[2]]
											  }],
---------------------------------- and so on.
 What does amp[i1,i2] = amplist[i1] [[i2]] [[3]] mean? I mean any
f[i.j]=g[i] [[j]] [[k]]
I am confused about the double-brackets used  [[----]].

2) in another expression,
itwo = StringPosition[jproc,"2"][[1,1]]

what for [[ x, y]] is used?

I'll be very grateful for your help.


--

Bob Hanlon



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