Results 1 to 3 of 3

Math Help - A function and a Hessian

  1. #1
    Member
    Joined
    Sep 2007
    Posts
    94

    A function and a Hessian

    For f(x,y) = root(25-x^2-y^2) calculate:

    a. the values: f(3,4)....easy! Just substitute, need no help here. And gradient f(3,4) = the partial derivatives df/dx and df/dy at the value 3,4...need help here. And finally the Hessian H (3,4) which is a matrix of second partial derivatives and the values need to be plugged in.

    While calculating the partial derivatives I get strange numbers or the answer 0 in every case. I don't think the answer is a matrix of zeros but the strange numbers I get if I do something else don't make much sense either.

    Try to tell me what to do.

    Thanks.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Member
    Joined
    Sep 2007
    Posts
    94
    Nevermind, the teacher changed the 25 in the function to 26 in his notes so I would get the value 1 and would be able to compute the Hessian. What a fruity teacher, I should have checked his rectified notes earlier.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Sep 2007
    Posts
    94
    I still need help though. What entries correspond to what in a Hessian matrix?

    Does it go like this for a 2 x 2 matrix -->
    x y
    y y


    And like this in a 3 x 3 matrix -->
    x y z
    y y z
    z z z

    ??

    Or in some other order?

    Help, thx.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 0
    Last Post: January 15th 2012, 01:32 PM
  2. Hessian
    Posted in the Differential Equations Forum
    Replies: 1
    Last Post: August 18th 2010, 05:11 PM
  3. Negative Hessian of a convex function
    Posted in the Calculus Forum
    Replies: 16
    Last Post: August 17th 2010, 02:19 AM
  4. Hessian matrix for 2d function
    Posted in the Differential Geometry Forum
    Replies: 2
    Last Post: September 27th 2009, 11:24 AM
  5. Replies: 0
    Last Post: February 6th 2009, 02:06 PM

Search Tags


/mathhelpforum @mathhelpforum