@Override
public MySparseVector iterationStep(MySparseVector x, MySparseMatrix m, MySparseVector b) {
int n = x.getSize();
List<MatrixItem> data = m.getData();
MySparseVector xnew = new MySparseVector(n);
int row = 0;
double rowsum = 0;
double diag = 0;
double value = 0;
for (MatrixItem i : data) {
if (i.getRow() != row) {
value = (b.getValue(row) - rowsum) * (1 / diag);
xnew.setValue(row, value);
row = i.getRow();
rowsum = 0;
}
if (i.getCol() == row) diag = i.getValue();
else rowsum += i.getValue() * x.getValue(i.getCol());
}
value = (b.getValue(row) - rowsum) * (1 / diag);
xnew.setValue(row, value);
return xnew;
}
public MySparseVector solve(MySparseMatrix a, MySparseVector b, MySparseVector x0) {
residuumNorms = new ArrayList<Double>();
qs = new ArrayList<Double>();
List<MySparseVector> xns = new ArrayList<MySparseVector>();
MySparseVector x = x0.clone();
MySparseVector resVector = b.substract(a.multiple(x));
residuumNorms.add(resVector.norm());
xns.add(x);
int i = 0;
boolean needMoreStep = true;
while (i < numberOfSteps && needMoreStep) {
x = iterationStep(x, a, b);
xns.add(x);
resVector = b.substract(a.multiple(x));
residuumNorms.add(resVector.norm());
if (i > 2) {
xns.remove(0);
double szamlalo = x.substract(xns.get(1)).norm();
double nevezo = xns.get(1).substract(xns.get(0)).norm();
if (nevezo == 0.0) {
needMoreStep = false;
} else {
double q = szamlalo / nevezo;
qs.add(q);
if (i > 5 && q > 1.5) {
needMoreStep = false;
}
}
}
++i;
}
lastStepNumber = i;
return x;
}