Example usage for org.apache.commons.math3.linear FieldMatrix setColumnVector

Introduction

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

Prototype

void setColumnVector(int column, FieldVector<T> vector)
        throws MatrixDimensionMismatchException, OutOfRangeException;

Source Link

Document

Set the entries in column number column as a vector.

Usage

From source file:model.LP.java

/**
 * Do one iteration of the simplex method.
 *
 * @param  entering/* ww w.  j a  v  a2s. c  o m*/
 *         Index of variable to enter the basis.
 * @param  leaving
 *         Index of variable to leave the basis.
 * @return
 *         A linear program after one iteration.
 */
public LP pivot(int entering, int leaving) {
    FieldMatrix<BigFraction> bin = new FieldLUDecomposition<BigFraction>(B_).getSolver().getInverse()
            .multiply(N_);

    // Step 1: Check for optimpivality
    // Step 2: Select entering variable.
    // Naive method. Does not check for optimality. Assumes feasibility.
    // Entering variable is given.

    // Step 3: Compute primal step direction.
    FieldVector<BigFraction> ej = new ArrayFieldVector<BigFraction>(bin.getColumnDimension(), BigFraction.ZERO);
    ej.setEntry(entering, BigFraction.ONE);
    FieldVector<BigFraction> psd = bin.operate(ej);

    // Step 4: Compute primal step length.
    // Step 5: Select leaving variable.
    // Leaving variable is given.
    BigFraction t = b_.getEntry(leaving).divide(psd.getEntry(leaving));

    // Step 6: Compute dual step direction.
    FieldVector<BigFraction> ei = new ArrayFieldVector<BigFraction>(bin.getRowDimension(), BigFraction.ZERO);
    ei.setEntry(leaving, BigFraction.ONE);
    FieldVector<BigFraction> dsd = bin.transpose().scalarMultiply(BigFraction.MINUS_ONE).operate(ei);

    // Step 7: Compute dual step length.
    BigFraction s = c_.getEntry(entering).divide(dsd.getEntry(entering));

    // Step 8: Update current primal and dual solutions.
    FieldVector<BigFraction> nb_ = b_.subtract(psd.mapMultiply(t));
    nb_.setEntry(leaving, t);

    FieldVector<BigFraction> nc_ = c_.subtract(dsd.mapMultiply(s));
    nc_.setEntry(entering, s);

    // Step 9: Update basis.
    FieldVector<BigFraction> temp = B_.getColumnVector(leaving);
    FieldMatrix<BigFraction> nB_ = B_.copy();
    nB_.setColumn(leaving, N_.getColumn(entering));

    FieldMatrix<BigFraction> nN_ = N_.copy();
    nN_.setColumnVector(entering, temp);

    int[] nBi = Bi.clone();
    int[] nNi = Ni.clone();
    nBi[leaving] = Ni[entering];
    nNi[entering] = Bi[leaving];

    return new LP(B, N, b, c, nB_, nN_, nb_, nc_, x, nBi, nNi);
}

---