mathematical expressions

This is a discussion on mathematical expressions within the C Programming forums, part of the General Programming Boards category; i got a trouble releated to a mathematical exp in c. i don not know how to evalate such an ...

  1. #1
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    Question mathematical expressions

    i got a trouble releated to a mathematical exp in c.

    i don not know how to evalate such an expression

    (third power of)x +(square of)x +23 = 0
    it is just an example.

    as u see we can not leave the x on one side of the equation so how can i solve such an expression?


    thanks

  2. #2
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    Re: mathematical expressions

    Originally posted by Unregistered
    how can i solve such an expression?
    There is no general rule on how to calculate a third degree equation when you have a constant on your left side (ax^3 + bx^2 + cx + d = 0. I believe there are some numerical way to solve it...
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  3. #3
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    Exclamation mis-understanding

    as i said it is just an example.

    the problem is i have an equation in this form

    (f + 1)^(n + 1) - (1+x/a)*(f+a)^n+x/a=0

    x,a,n is given and i want to calculate f but i can t find such an expression f=...... it is possible to write it in this manner.
    what should i do?

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    I dont know of a algebraic way of solving it, but there is a method I know of that can give you an estimate to any desired accuracy, called the Newton-Raphson (or something like that) method, but it involves calculating the derivative of your funtion. Although there is the secant method that doesnt involve calculating derivatives which works just as well. I dont remember it off the top of my head but I can look it up of you like.

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    hmmm, just thought of something else, since im assuming you need to evaluate that equation using a program, you can use the "divide-and-conquer" method. Its pretty simple to implement, since it only involves using the actual equation and calculating averages.

  6. #6
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    Question

    Hi,

    just thinking there that it may also be usefull if you told us what you were going to do with the solution,

    is it not common in graphics to turn this sort of equation into a parametric equation? so you can solve over values of t if your plotting the solution?

    this is off the top of my head so not too sure if its acurate....

  7. #7
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    Talking thanks

    thanks to all i solve it

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