Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Equation and write the procedure? x+cos(x)=0

  1. Mar 28, 2005 #1
    Can someone solve this equation and write the procedure?

    x+cos(x)=0

    Without using graph.
     
  2. jcsd
  3. Mar 28, 2005 #2
    cos(x) is a transcendental function, there isn't much point to scratching your head trying to solve a transcendental equation; it isn't likely to be expressible in terms of radicals anyway.

    Use Newtons method.
     
  4. Mar 28, 2005 #3

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    The approximate solution is all u could get...The solution is unique,however,it is certainly a transcendental (i.e.no algebraic) number...

    Daniel.
     
  5. Mar 28, 2005 #4
    cos(x)=0,3 is also transcendental equation (I think), even so I can get approximate solution with my calculator (1,266 ...). Is there any possibility how to get approximate solution of x+cos(x)=0 with common calculator (for example the calculator in windows)?
     
  6. Mar 28, 2005 #5

    Integral

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Express the equation as:

    x = - Cos(x)

    now do a fixed point iteration so

    [tex] x_2 = - \cos (x_1) [/tex]
    and
    [tex] x_{n +1} = - \cos (x_n) [/tex]


    Start by making a guess between 1 and 0, call this [itex] x_1 [/itex] calculate [itex] x_2 [/itex] ,simply repeat the process until the number stops changing. It is not incredibly fast, 20 iterations gets you around 3 digits. Keep iterating until you are tired of pushing buttons, observe the digits that do not change. The unchanging digits are your answer. If you want more digits iterate some more.
     
  7. Mar 28, 2005 #6
    Thank you, I think this is sufficient for me.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Equation and write the procedure? x+cos(x)=0
  1. X/0 = ? (Replies: 8)

  2. Cos(x) = x (Replies: 7)

  3. X-x = 0 (Replies: 36)

  4. Tan x = cos x (Replies: 12)

Loading...