Finding roots on an equation

[Fede85]

Hello, this is the first time that I program with C++. I want create a program to able to compute the root of an equation with unknown degree. I want to use "boost" library but I don't understand which is the best function to use and how to use it.

I am using Visual c++ express.

I hope you understand me and my english!!

Thanks

[Moschops]

You have to start by writing out the steps that need to be followed exactly to solve such an equation.

[Fede85]

If the degree of equation is equal to 2 or 3 the formula for solve this is known but if the degree of equation is > or = to 4 i have problems. I want create a general function.

I saw that in boost library (boost::math::tool) there are some function (i.e. bisect) for solve this problem but i don't understand how i can use this.

Thanks

[ashishkumar]

Try these steps
Suppose Y = F(x) is your equation
1) Get the X values and corresponding Y values in two different arrays.
2) Find the derrivative of Y ( w.r.t X) i.e dY/dX
3) Scan the resultant for 0 values. Root => dY=dX is 0.
Try this link...
http://www.boost.org/doc/libs/1_37_0/libs/math/doc/sf_and_dist/html/math_toolkit/toolkit/internals1/roots.html

[kev82]

I don't know the bisect function, but I would assume it goes something like this.

This only applies to real roots, not complex ones.

Let a<b. By the intermediate value theorem, a continuous function that satisfies f(a)<0<f(b) or f(a)>0>f(b) must have a root between a and b. Let c = (b-a)/2 and consider the two regions [a,c] and [c,b]. One of these regions must contain the root in [a,b]. Reapply the theorem until b-a is within your desired accuracy.