/**
* Function to compute matrix inverse via matrix decomposition.
*
* @param in commons-math3 Array2DRowRealMatrix
* @return matrix block
* @throws DMLRuntimeException if DMLRuntimeException occurs
*/
private static MatrixBlock computeMatrixInverse(Array2DRowRealMatrix in)
throws DMLRuntimeException {
if (!in.isSquare())
throw new DMLRuntimeException(
"Input to inv() must be square matrix -- given: a "
+ in.getRowDimension()
+ "x"
+ in.getColumnDimension()
+ " matrix.");
QRDecomposition qrdecompose = new QRDecomposition(in);
DecompositionSolver solver = qrdecompose.getSolver();
RealMatrix inverseMatrix = solver.getInverse();
return DataConverter.convertToMatrixBlock(inverseMatrix.getData());
}
/**
* Function to solve a given system of equations.
*
* @param in1 matrix object 1
* @param in2 matrix object 2
* @return matrix block
* @throws DMLRuntimeException if DMLRuntimeException occurs
*/
private static MatrixBlock computeSolve(MatrixObject in1, MatrixObject in2)
throws DMLRuntimeException {
Array2DRowRealMatrix matrixInput = DataConverter.convertToArray2DRowRealMatrix(in1);
Array2DRowRealMatrix vectorInput = DataConverter.convertToArray2DRowRealMatrix(in2);
/*LUDecompositionImpl ludecompose = new LUDecompositionImpl(matrixInput);
DecompositionSolver lusolver = ludecompose.getSolver();
RealMatrix solutionMatrix = lusolver.solve(vectorInput);*/
// Setup a solver based on QR Decomposition
QRDecomposition qrdecompose = new QRDecomposition(matrixInput);
DecompositionSolver solver = qrdecompose.getSolver();
// Invoke solve
RealMatrix solutionMatrix = solver.solve(vectorInput);
return DataConverter.convertToMatrixBlock(solutionMatrix.getData());
}
/* 91: */
/* 92: */ public Array2DRowRealMatrix initializeHighOrderDerivatives(
double h, double[] t, double[][] y, double[][] yDot)
/* 93: */ {
/* 94:259 */ double[][] a = new double[2 * (y.length - 1)][this.c1.length];
/* 95:260 */ double[][] b = new double[2 * (y.length - 1)][y[0].length];
/* 96:261 */ double[] y0 = y[0];
/* 97:262 */ double[] yDot0 = yDot[0];
/* 98:263 */ for (int i = 1; i < y.length; i++)
/* 99: */ {
/* 100:265 */ double di = t[i] - t[0];
/* 101:266 */ double ratio = di / h;
/* 102:267 */ double dikM1Ohk = 1.0D / h;
/* 103: */
/* 104: */
/* 105: */
/* 106:271 */ double[] aI = a[(2 * i - 2)];
/* 107:272 */ double[] aDotI = a[(2 * i - 1)];
/* 108:273 */ for (int j = 0; j < aI.length; j++)
/* 109: */ {
/* 110:274 */ dikM1Ohk *= ratio;
/* 111:275 */ aI[j] = (di * dikM1Ohk);
/* 112:276 */ aDotI[j] = ((j + 2) * dikM1Ohk);
/* 113: */ }
/* 114:280 */ double[] yI = y[i];
/* 115:281 */ double[] yDotI = yDot[i];
/* 116:282 */ double[] bI = b[(2 * i - 2)];
/* 117:283 */ double[] bDotI = b[(2 * i - 1)];
/* 118:284 */ for (int j = 0; j < yI.length; j++)
/* 119: */ {
/* 120:285 */ bI[j] = (yI[j] - y0[j] - di * yDot0[j]);
/* 121:286 */ yDotI[j] -= yDot0[j];
/* 122: */ }
/* 123: */ }
/* 124:294 */ QRDecomposition decomposition =
new QRDecomposition(new Array2DRowRealMatrix(a, false));
/* 125:295 */ RealMatrix x =
decomposition.getSolver().solve(new Array2DRowRealMatrix(b, false));
/* 126:296 */ return new Array2DRowRealMatrix(x.getData(), false);
/* 127: */ }