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Re: partial transpose

  • To: mathgroup at smc.vnet.net
  • Subject: [mg125506] Re: partial transpose
  • From: Bill Rowe <readnews at sbcglobal.net>
  • Date: Fri, 16 Mar 2012 06:31:56 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com

On 3/15/12 at 12:26 AM, kjsalini at gmail.com (jay) wrote:

>how to find partial transpose of a density matrix

How about defining what you mean by a partial transpose?

Perhaps something like:

In[5]:= a = RandomInteger[10, {5, 5}]

Out[5]= {{9, 2, 6, 5, 3}, {5, 2, 10, 6, 2}, {4, 7, 8, 6, 9}, {4, 10,
  8, 3, 4}, {0, 0, 0, 9, 2}}

In[6]:= mask =
  Unitize[1 - SparseArray[{Band[{3, 3}] -> Unitize[a[[;; 3, ;; 3]]]}]];

In[7]:= a mask +
  SparseArray[{Band[{3, 3}] -> Transpose[a[[3 ;;, 3 ;;]]]}] // Normal

Out[7]= {{9, 2, 6, 5, 3}, {5, 2, 10, 6, 2}, {4, 7, 8, 8, 0}, {4, 10,
  6, 3, 9}, {0, 0, 9, 4, 2}}




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