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Newton Raphson Method on Fortran90

  1. Dec 2, 2012 #1
    Here's what I need to do:

    "Compare the effectiveness of the bisection method and Newton’s method for the
    equation x^3−2x−2 = 0 which has a single root between x=−4 and x = 2."


    So far I've done
    jsyq0z.jpg
    ok. this is working but of course I need to do iteration which I don't know how. Can someone teach me please? I'm trying the Newton-Raphson Method first.

    Thanks for the help in advance.


    EDITED: Sorry, I posted the wrong pic earlier. Here's the correct one.
     
    Last edited: Dec 2, 2012
  2. jcsd
  3. Dec 2, 2012 #2
    Code (Text):

    program nr
    real:: x, xnew, err

    write(*,*) "starting x?:"
    read(*,*) x

    do
        xnew = x - ( (x**3 - (2*x) - 2) / ( ( 3*(x**2) )-2) )
        err = 100*abs( (xnew-x)/x )
        x = xnew
        write(*,*) "x = ", xnew, "  error = ", err
        if (err < 0.000001) exit
    end do

    end program nr
     
     
  4. Dec 3, 2012 #3
    thanks :))) Is that the iteration already?
     
  5. Dec 3, 2012 #4
    Yes.

    Isn't it? Run it and verify the solution
     
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