public static int SolveSeidel(DiagMatrix mat, Vector vec, Vector start, double weight)
{
int size = mat.size;
int diagCount = mat.diagCount;
int mainDiagIndex = Array.IndexOf(mat.offsets, 0);
double[,] values = mat.values;
int[] offsets = mat.offsets;
double[] v = vec.values;
double[] x = start.values;
int i, j;
double collector;
int step;
double norm = 0;
double curNorm;
int offset;
double residual;
for (i = 0; i < size; i++)
{
norm += v[i] * v[i];
}
for (step = 0; step < MaxSteps; step++)
{
curNorm = 0;
for (i = 0; i < size; i++)
{
collector = 0;
for (j = 0; j < diagCount; j++)
{
offset = i + offsets[j];
if (offset < 0)
{
continue;
}
if (offset >= size)
{
break;
}
collector += values[j, i] * x[offset];
}
x[i] += weight * (v[i] - collector) / values[mainDiagIndex, i];
curNorm += (v[i] - collector) * (v[i] - collector);
}
residual = Math.Sqrt(curNorm / norm);
//Console.WriteLine("step = " + (step + 1) + ", residual = " + residual);
if (residual < Epsilon)
{
break;
}
}
return(step + 1);
}
public static int SolveJacobi(DiagMatrix mat, Vector vec, Vector start, double epsilon, double weight)
{
int size = mat.size;
int diagCount = mat.diagCount;
int mainDiagIndex = Array.IndexOf(mat.offsets, 0);
double[,] values = mat.values;
int[] offsets = mat.offsets;
double[] v = vec.values;
double[] x = start.values;
int i, j, k;
double[] collector = new double[size];
int step;
double norm = 0;
double curNorm;
double residual;
for (i = 0; i < size; i++)
{
norm += v[i] * v[i];
}
for (step = 0; step < MaxSteps; step++)
{
curNorm = 0;
for (i = 0; i < diagCount; i++)
{
for (j = Math.Max(-offsets[i], 0), k = Math.Max(offsets[i], 0); j < size && k < size; j++, k++)
{
collector[j] += x[k] * values[i, j];
}
}
for (i = 0; i < size; i++)
{
curNorm += (v[i] - collector[i]) * (v[i] - collector[i]);
x[i] += weight * (v[i] - collector[i]) / values[mainDiagIndex, i];
collector[i] = 0;
}
residual = Math.Sqrt(curNorm / norm);
//Console.WriteLine("step = " + (step + 1) + ", residual = " + residual);
if (residual < epsilon)
{
break;
}
}
return(step + 1);
}
