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A quick matrix question

  • 21-04-2008 2:34pm
    #1
    Closed Accounts Posts: 842 ✭✭✭


    Hey, just a quick one, can anyone tell me how to find A*? Not sure what the "*" is looking for. (I'm working with 3x3 matrices)

    Cheers.


Comments

  • Registered Users, Registered Users 2 Posts: 12,049 ✭✭✭✭L'prof


    Weidii wrote: »
    Hey, just a quick one, can anyone tell me how to find A*? Not sure what the "*" is looking for. (I'm working with 3x3 matrices)

    Cheers.

    Can you give me some background info? What course are you doing, what year are you in?

    What's the full question?

    I presume they're either looking for the transpose or the inverse!


  • Closed Accounts Posts: 842 ✭✭✭Weidii


    I'm doing maths as part of first year science in NUIGalway. We have a calculus and algebra module. I came across this notation on the exam papers and it threw me a bit, just not sure what it's asking. I have the feeling it means transpose, but am just wondering if anyone knows for sure.


  • Registered Users, Registered Users 2 Posts: 2,481 ✭✭✭Fremen


    Does it not tell you on the exam paper?
    Notation differs from between courses. I've seen T, ' and * all used for transpose.

    If it's a first-year linear algebra course, it propably does mean transpose, but without more context we won't be able to say for sure.


  • Moderators, Science, Health & Environment Moderators Posts: 1,852 Mod ✭✭✭✭Michael Collins


    Often A* means the Hermetian Transpose, which would mean take the transpose and then the complex conjugate of each entry. But as Fremen says the notation varies. Are there complex entries in the matrix?


  • Closed Accounts Posts: 842 ✭✭✭Weidii


    No complex entries. I'm pretty sure it means the transpose. Thanks guys.


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  • Registered Users, Registered Users 2 Posts: 12,049 ✭✭✭✭L'prof


    Weidii wrote: »
    No complex entries. I'm pretty sure it means the transpose. Thanks guys.

    I think you're right because I actually did those subjects last year and nothing compicated than Inverse & Transpose came up!


  • Moderators, Science, Health & Environment Moderators Posts: 1,852 Mod ✭✭✭✭Michael Collins


    Either way it's the same - the complex conjugate of a real number is just the same number again, so it ends up just be the transpose anyway...


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