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Re: what's wrong?!!

  • To: mathgroup at smc.vnet.net
  • Subject: [mg115835] Re: what's wrong?!!
  • From: Peter Pein <petsie at dordos.net>
  • Date: Sat, 22 Jan 2011 03:22:01 -0500 (EST)
  • References: <ih16b7$jiq$1@smc.vnet.net> <ih3rd0$bga$1@smc.vnet.net> <ihbjk9$d9n$1@smc.vnet.net>

On 21.01.2011 10:28, olfa wrote:

>
> still have problem with Cases for another example:
>
> Cases[A[l1] == A[l2]&&  i + B[l2] == iP + B[l1], A | B, {0, Infinity}]
>
> returns {} why?!
>

Hi,

A and B are heads of expressions and therefore match _A|_B

In[1]:= Cases[
  A[l1] == A[l2] && i + B[l2] == iP + B[l1], _A | _B, {0, Infinity}]

Out[1]= {A[l1], A[l2], B[l2], B[l1]}

if you want the heads only append "[[All, 0]]" to the above line to get

In[2]:= %[[All, 0]]

Out[2]= {A, A, B, B}


Cheers,
Peter


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