com.wwidesigner.math.StateVector.java Source code

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Here is the source code for com.wwidesigner.math.StateVector.java

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/**
 * Class to manage acoustic state vectors with two elements: pressure and volume flow.
 * 
 * Copyright (C) 2014, Edward Kort, Antoine Lefebvre, Burton Patkau.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.wwidesigner.math;

import org.apache.commons.math3.complex.Complex;

/**
 * @author kort
 * 
 */
public class StateVector {

    protected Complex mP;
    protected Complex mU;

    /**
     * Simple 2x1 complex vector representing the state of the air column at a
     * point in the bore. P refers to the pressure and U to the volume flow.
     */
    public StateVector() {
        mP = Complex.ZERO;
        mU = Complex.ZERO;
    }

    public StateVector(Complex p, Complex u) {
        mP = TransferMatrix.copyComplex(p);
        mU = TransferMatrix.copyComplex(u);
    }

    public StateVector(StateVector from) {
        mP = TransferMatrix.copyComplex(from.mP);
        mU = TransferMatrix.copyComplex(from.mU);
    }

    /**
     * @return a state vector representing an ideal open end.
     */
    public static StateVector OpenEnd() {
        // At an open end, pressure is zero.
        return new StateVector(Complex.ZERO, Complex.ONE);
    }

    /**
     * @return a state vector representing an ideal closed end.
     */
    public static StateVector ClosedEnd() {
        // At a closed end, acoustic flow is zero.
        return new StateVector(Complex.ONE, Complex.ZERO);
    }

    /**
     * @return the impedance (Z) that a component with this state vector is
     *         presenting
     */
    public Complex getImpedance() {
        return mP.divide(mU);
    }

    /**
     * @return the admittance (Y) that a component with this state vector is
     *         presenting
     */
    public Complex getAdmittance() {
        return mU.divide(mP);
    }

    /**
     * @return the reflectance (coefficient of reflection of pressure)
     *         that a component with this state vector is presenting
     */
    public Complex getReflectance(double Z0) {
        return mP.subtract(mU.multiply(Z0)).divide(mP.add(mU.multiply(Z0)));
    }

    /**
     * Add another state vector in series with this.
     * @param other
     * @return sv that satisfies sv.getImpedance() = this.getImpedance() + other.getImpedance().
     */
    public StateVector series(StateVector other) {
        Complex newP = this.mP.multiply(other.mU).add(other.mP.multiply(this.mU));
        Complex newU = this.mU.multiply(other.mU);
        return new StateVector(newP, newU);
    }

    /**
     * Add another state vector in parallel with this.
     * @param other
     * @return sv that satisfies 1/sv.getImpedance() = 1/this.getImpedance() + 1/other.getImpedance().
     */
    public StateVector parallel(StateVector other) {
        Complex newU = this.mP.multiply(other.mU).add(other.mP.multiply(this.mU));
        Complex newP = this.mP.multiply(other.mP);
        return new StateVector(newP, newU);
    }
}