// Opposite of a matrix [static method]
public static MatrixError opposite(MatrixError amat) {
MatrixError opp = MatrixError.copy(amat);
for (int i = 0; i < amat.nrow; i++) {
for (int j = 0; j < amat.ncol; j++) {
opp.matrix[i][j] = -amat.matrix[i][j];
}
}
return opp;
}
// OPPOSITE
// Opposite of a matrix [instance method]
public MatrixError opposite() {
MatrixError opp = MatrixError.copy(this);
for (int i = 0; i < this.nrow; i++) {
for (int j = 0; j < this.ncol; j++) {
opp.matrix[i][j] = -this.matrix[i][j];
}
}
return opp;
}
// LU DECOMPOSITION OF COMPLEX MATRIX A
// For details of LU decomposition
// See Numerical Recipes, The Art of Scientific Computing
// by W H Press, S A Teukolsky, W T Vetterling & B P Flannery
// Cambridge University Press, http://www.nr.com/
// Matrix ludmat is the returned LU decompostion
// int[] index is the vector of row permutations
// dswap returns +1.0 for even number of row interchanges
// returns -1.0 for odd number of row interchanges
public MatrixError luDecomp() {
if (this.nrow != this.ncol) throw new IllegalArgumentException("A matrix is not square");
int n = this.nrow;
int imax = 0;
double dum = 0.0D, temp = 0.0D, big = 0.0D;
double[] vv = new double[n];
double sum = 0.0D;
double dumm = 0.0D;
this.matrixCheck = true;
MatrixError ludmat = MatrixError.copy(this);
double[][] ludarray = ludmat.getArrayReference();
ludmat.dswap = 1.0D;
for (int i = 0; i < n; i++) {
big = 0.0D;
for (int j = 0; j < n; j++) if ((temp = Math.abs(ludarray[i][j])) > big) big = temp;
if (big == 0.0D) {
System.out.println("Attempted LU Decomposition of a singular matrix in Matrix.luDecomp()");
System.out.println("NaN matrix returned and matrixCheck set to false");
this.matrixCheck = false;
for (int k = 0; k < n; k++) for (int j = 0; j < n; j++) ludarray[k][j] = Double.NaN;
return ludmat;
}
vv[i] = 1.0 / big;
}
for (int j = 0; j < n; j++) {
for (int i = 0; i < j; i++) {
sum = ludarray[i][j];
for (int k = 0; k < i; k++) sum -= ludarray[i][k] * ludarray[k][j];
ludarray[i][j] = sum;
}
big = 0.0D;
for (int i = j; i < n; i++) {
sum = ludarray[i][j];
for (int k = 0; k < j; k++) sum -= ludarray[i][k] * ludarray[k][j];
ludarray[i][j] = sum;
if ((dum = vv[i] * Math.abs(sum)) >= big) {
big = dum;
imax = i;
}
}
if (j != imax) {
for (int k = 0; k < n; k++) {
dumm = ludarray[imax][k];
ludarray[imax][k] = ludarray[j][k];
ludarray[j][k] = dumm;
}
ludmat.dswap = -ludmat.dswap;
vv[imax] = vv[j];
}
ludmat.index[j] = imax;
if (ludarray[j][j] == 0.0D) {
ludarray[j][j] = TINY;
}
if (j != n - 1) {
dumm = 1.0 / ludarray[j][j];
for (int i = j + 1; i < n; i++) {
ludarray[i][j] *= dumm;
}
}
}
return ludmat;
}
