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20.3 Example Program - Roots of a Polynomial
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20.3 Example Program - Roots of a Polynomial
Obtaining the Sample Program
The roots of a polynomial a x2 + b x + c = 0 are given by the formula:
x = (-b _ sqrt(b2 - 4ac))/2a
The following program takes as input three double precision numbers, and returns the complex roots as a pair of values.
typedef complex<double> dcomplex;
pair<dcomplex, dcomplex> quadratic
(dcomplex a, dcomplex b, dcomplex c)
// return the roots of a quadratic equation
{
dcomplex root = sqrt(b * b - 4.0 * a * c);
a *= 2.0;
return make_pair(
(-b + root)/a,
(-b - root)/a);
}
©Copyright 1996, Rogue Wave Software, Inc.
