InvertMatrix.java

package org.nd4j.linalg.inverse;

import org.apache.commons.math3.linear.LUDecomposition;
import org.apache.commons.math3.linear.RealMatrix;
import org.nd4j.linalg.api.ndarray.INDArray;
import org.nd4j.linalg.checkutil.CheckUtil;

/**
 * Created by agibsoncccc on 11/30/15.
 */
public class InvertMatrix {


    /**
     * Inverts a matrix
     * @param arr the array to invert
     * @return the inverted matrix
     */
    public static INDArray invert(INDArray arr, boolean inPlace) {
        if (!arr.isSquare()) {
            throw new IllegalArgumentException("invalid array: must be square matrix");
        }

        //FIX ME: Please
        //int[] IPIV = new int[arr.length() + 1];
        //int LWORK = arr.length() * arr.length();
        //INDArray WORK = Nd4j.create(new double[LWORK]);
        //INDArray inverse = inPlace ? arr : arr.dup();
        //Nd4j.getBlasWrapper().lapack().getrf(arr.size(1),arr.size(0),inverse, arr.size(0),IPIV,0);
        //Nd4j.getBlasWrapper().lapack().getri(arr.size(0),inverse,arr.size(0),IPIV,WORK,LWORK,0);

        RealMatrix rm = CheckUtil.convertToApacheMatrix(arr);
        RealMatrix rmInverse = new LUDecomposition(rm).getSolver().getInverse();

        INDArray inverse = CheckUtil.convertFromApacheMatrix(rmInverse);
        if (inPlace)
            arr.assign(inverse);
        return inverse;

    }

}