Results 1 to 2 of 2

Math Help - Help with partial derivatives for linear least squares

  1. #1
    Newbie
    Joined
    Nov 2008
    Posts
    1

    Help with partial derivatives for linear least squares

    I am refered to this example:

    Linear least squares - Wikipedia, the free encyclopedia

    If I understand right, the solution of the system

    S'b(a)=0
    S'a(b)=0

    gives the values a=3.5 and b=1.4, for witch the S(a,b) takes the minimum value.

    I try to find this results myself, but when I calculate the partial derivatives with respect to a and b of S(a,b), I find:

    S'b(a) = 8a+20b-56 (b=constant) ( I thing this is right ) and
    S'a(b) = 20a+20b-154 (a=constant) (this dont' fit the results)

    probably somewhere I make a mistake ... but where ?

    Thanks in advance
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Nov 2008
    From
    France
    Posts
    1,458
    Quote Originally Posted by bopistas View Post
    S'a(b) = 20a+20b-154 (a=constant) (this dont' fit the results)
    Correct equation is S'a(b) = 20a+60b-154
    It comes from
    -2(6-a-b)-4(5-a-2b)-6(7-a-3b)-8(10-a-4b)
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Linear least squares with constraints
    Posted in the Advanced Algebra Forum
    Replies: 0
    Last Post: November 27th 2011, 04:55 PM
  2. Linear Regression, Residual Sum of Squares
    Posted in the Advanced Statistics Forum
    Replies: 0
    Last Post: November 25th 2011, 12:16 PM
  3. Help to formulate a non linear least squares problem
    Posted in the Advanced Applied Math Forum
    Replies: 0
    Last Post: August 20th 2011, 01:51 AM
  4. Help with non-linear least squares
    Posted in the Differential Geometry Forum
    Replies: 3
    Last Post: February 24th 2011, 11:01 AM
  5. linear algebra least squares solution
    Posted in the Advanced Algebra Forum
    Replies: 0
    Last Post: August 16th 2010, 09:41 PM

Search Tags


/mathhelpforum @mathhelpforum