Berkeley CSUA MOTD:Entry 24746
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2025/05/27 [General] UID:1000 Activity:popular
5/27    

2002/5/7-8 [Computer/Theory] UID:24746 Activity:high
5/7     Say you have a matrix A, and they say that A * A^-1 = 1 (right?)
        How does one get A^-1?
        \_ you'd think if you were going to post some simple math question,
           you would first read the replys to the previous one.
           http://www.mathworld.com has the answeres to all of these questions,
           with links to related questions, great examples, etc.
           that should be your fist stop, not the motd.
        \_ one takes math 54
        \_ obviously A^1 is the same a 1/A.
        \_ for a 2x2 matrix, it's trivial. for larger matrices, check out
           a linear algebra reference for details.  but for now:
           (a b) ^-1  =  M(d -b)    where M = 1/(determinant)
           (c d)          (-c a)
2025/05/27 [General] UID:1000 Activity:popular
5/27    

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Cache (839 bytes)
www.mathworld.com -> mathworld.wolfram.com/
NKS 2004 Conference to Be Held in Boston NKS 2004, the second conference and minicourse devoted to the concepts in Stephen Wolfram's A New Kind of Science (NKS), will take place this April 22-25 in Boston. Arbitrarily Long Progressions of Primes A new preprint by Green and Tao appears to establish the existence of prime arithmetic progressions of any length k, a result that has been conjectured for three quarters of a century but until now has defied proof. New NKS|Online, Functions, and MathWorld Websites Unveiled 2004 brings the rollout of NKS|Online, a major upgrade to The Wolfram Functions Site, and a new look for MathWorld to the internet. RSA-576 Factored A 174-digit number proposed as a challenge for current factorization algorithms has been factored into two 87-digit primes. References Visible links 1. Hidden links: 39.