我需要找到一个(近似的,数值的)解勒让德多项式。我尝试了几个Java库,但没有一个有我正在寻找的东西(最接近的是commons-math,它甚至有用于在拉盖尔求解器,但它没有公开该方法)。是否有现有的解决方案或者我需要实施自己的解决方案?
您可以使用EJML (高效的Java矩阵库).
请查找以下示例。
public class PolynomialRootFinder {
/**
* <p>
* Given a set of polynomial coefficients, compute the roots of the polynomial. Depending on
* the polynomial being considered the roots may contain complex number. When complex numbers are
* present they will come in pairs of complex conjugates.
* </p>
*
* @param coefficients Coefficients of the polynomial.
* @return The roots of the polynomial
*/
public static Complex64F[] findRoots(double... coefficients) {
int N = coefficients.length-1;
// Construct the companion matrix
DenseMatrix64F c = new DenseMatrix64F(N,N);
double a = coefficients[N];
for( int i = 0; i < N; i++ ) {
c.set(i,N-1,-coefficients[i]/a);
}
for( int i = 1; i < N; i++ ) {
c.set(i,i-1,1);
}
// Use generalized eigenvalue decomposition to find the roots
EigenDecomposition<DenseMatrix64F> evd = DecompositionFactory.eigGeneral(N, false);
evd.decompose(c);
Complex64F[] roots = new Complex64F[N];
for( int i = 0; i < N; i++ ) {
roots[i] = evd.getEigenvalue(i);
}
return roots;
}
}
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