Example usage for org.apache.commons.math3.linear RealVector getMaxValue

Introduction

In this page you can find the example usage for org.apache.commons.math3.linear RealVector getMaxValue.

Prototype

public double getMaxValue() 

Source Link

Document

Get the value of the maximum entry.

Usage

From source file:net.sf.dsp4j.octave_3_2_4.m.polynomial.Roots.java

public static Complex[] roots(RealVector v) {

    if (v.isInfinite() || v.isNaN()) {
        throw new RuntimeException("roots: inputs must not contain Inf or NaN");
    }//  ww w .  ja  v  a 2  s .c  o m

    int n = v.getDimension();

    // ## If v = [ 0 ... 0 v(k+1) ... v(k+l) 0 ... 0 ], we can remove the
    // ## leading k zeros and n - k - l roots of the polynomial are zero.

    int[] f = new int[v.getDimension()];
    if (v.getDimension() > 0) {
        int fI = 0;
        double max = v.getMaxValue();
        double min = FastMath.abs(v.getMinValue());
        if (min > max) {
            max = min;
        }
        RealVector v1 = v.mapDivide(max);
        f = OctaveBuildIn.find(v1);
    }

    Complex[] r = new Complex[0];
    if (f.length > 0 && n > 1) {
        v = v.getSubVector(f[0], f[f.length - 1] - f[0] + 1);
        if (v.getDimension() > 1) {
            double[] ones = new double[v.getDimension() - 2];
            Arrays.fill(ones, 1);
            RealMatrix A = OctaveBuildIn.diag(ones, -1);
            for (int i = 0; i < A.getRowDimension(); i++) {
                A.setEntry(i, 0, -v.getEntry(i + 1) / v.getEntry(0));
            }
            try {
                r = Eig.eig(A);
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
            if (f[f.length - 1] < n) {
                int diffLength = n - 1 - f[f.length - 1];
                if (diffLength > 0) {
                    int rl = r.length;
                    r = Arrays.copyOf(r, r.length + diffLength);
                    Arrays.fill(r, rl, r.length, Complex.ZERO);
                }
            }
        } else {
            r = new Complex[n - f[f.length - 1]];
            Arrays.fill(r, Complex.ZERO);
        }
    } else {
        r = new Complex[0];
    }
    return r;

}

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