public static double[] Skew(double[] vec, double theta)
{
double cos = System.Math.Cos(theta);
double sin = System.Math.Sin(theta);
double[,] m = new double[, ] {
{ cos, 0.0, 0.0 },
{ sin, 1.0, 0.0 },
{ 0.0, 0.0, 1.0 }
};
NcvMatrix mat = new NcvMatrix(m);
return(mat.Multiply(vec));
}
public static double[] Rotate(double[] vec, double alpha)
{
double cos = System.Math.Cos(alpha);
double sin = System.Math.Sin(alpha);
double[,] m = new double[, ] {
{ cos, -sin, 0.0 },
{ sin, cos, 0.0 },
{ 0.0, 0.0, 1.0 }
};
NcvMatrix mat = new NcvMatrix(m);
return(mat.Multiply(vec));
}
public static NcvMatrix del2(NcvMatrix m)
{
int rows = m.rows();
int cols = m.cols();
/* IV: Compute Laplace operator using Neuman condition */
/* IV.1: Deal with corners */
NcvMatrix Lu = new NcvMatrix(cols, rows);
int rows_1 = rows - 1; int rows_2 = rows - 2;
int cols_1 = cols - 1; int cols_2 = cols - 2;
Lu[0, 0] = (m[0, 1] + m[1, 0]) * 0.5 - m[0, 0];
Lu[cols_1, 0] = (m[cols_2, 0] + m[cols_1, 1]) * 0.5 - m[cols_1, 0];
Lu[0, rows_1] = (m[1, rows_1] + m[0, rows_2]) * 0.5 - m[0, rows_1];
Lu[cols_1, rows_1] = (m[cols_2, rows_1] + m[cols_1, rows_2]) * 0.5 - m[cols_1, rows_1];
/* IV.2: Deal with left and right columns */
for (int y = 1; y <= rows_2; y++)
{
Lu[0, y] = (2 * m[1, y] + m[0, y - 1] + m[0, y + 1]) * 0.25 - m[0, y];
Lu[cols_1, y] = (2 * m[cols_2, y] + m[cols_1, y - 1]
+ m[cols_1, y + 1]) * 0.25 - m[cols_1, y];
}
/* IV.3: Deal with top and bottom rows */
for (int x = 1; x <= cols_2; x++)
{
Lu[x, 0] = (2 * m[x, 1] + m[x - 1, 0] + m[x + 1, 0]) * 0.25 - m[x, 0];
Lu[x, rows_1] = (2 * m[x, rows_2] + m[x - 1, rows_1]
+ m[x + 1, rows_1]) * 0.25 - m[x, rows_1];
}
/* IV.4: Compute interior */
for (int y = 1; y <= rows_2; y++)
{
for (int x = 1; x <= cols_2; x++)
{
Lu[x, y] = (m[x - 1, y] + m[x + 1, y]
+ m[x, y - 1] + m[x, y + 1]) * 0.25 - m[x, y];
}
}
return(Lu);
}
public static NcvMatrix diag(NcvVector v, int k)
{
int n = v.n;
int order = n + Math.Abs(k);
NcvMatrix m = new NcvMatrix(order, order);
for (int i = 0; i < n; i++)
{
if (k <= 0)
{
m[i, i - k] = v[i];
}
else
{
m[i + k, i] = v[i];
}
}
return(m);
}
public override bool Equals(object obj)
{
NcvMatrix other = (NcvMatrix)obj;
if (this.Rows != other.Rows ||
this.Cols != other.Cols)
{
return(false);
}
for (int y = 0; y < this.rows(); y++)
{
for (int x = 0; x < this.cols(); x++)
{
if (this[x, y] != other[x, y])
{
return(false);
}
}
}
return(true);
}
public NcvMatrix(NcvMatrix M)
{
data = new double[M.rows(), M.cols()];
copy(M);
}
public static NcvMatrix inv(NcvMatrix original)
{
NcvMatrix inv = new NcvMatrix(original.cols(), original.rows());
return(inv.inverse(original));
}
// sets this Matrix to the inverse of the original Matrix
// and returns this.
public NcvMatrix inverse(NcvMatrix original)
{
if (original.rows() < 1 || original.rows() != original.cols() ||
rows() != original.rows() || rows() != cols())
{
return(this);
}
int n = rows();
copy(new NcvMatrix(n)); // make identity matrix
if (rows() == 1)
{
this[0, 0] = 1 / original[0, 0];
return(this);
}
NcvMatrix b = new NcvMatrix(original);
for (int i = 0; i < n; i++)
{
// find pivot
double mag = 0;
int pivot = -1;
for (int j = i; j < n; j++)
{
double mag2 = Math.Abs(b[j, i]);
if (mag2 > mag)
{
mag = mag2;
pivot = j;
}
}
// no pivot (error)
if (pivot == -1 || mag == 0)
{
return(this);
}
// move pivot row into position
if (pivot != i)
{
double temp;
for (int j = i; j < n; j++)
{
temp = b[i, j];
this[i, j] = b[pivot, j];
b[pivot, j] = temp;
}
for (int j = 0; j < n; j++)
{
temp = this[i, j];
this[i, j] = this[pivot, j];
this[pivot, j] = temp;
}
}
// normalize pivot row
mag = b[i, i];
for (int j = i; j < n; j++)
{
b[i, j] = b[i, j] / mag;
}
for (int j = 0; j < n; j++)
{
this[i, j] = this[i, j] / mag;
}
// eliminate pivot row component from other rows
for (int k = 0; k < n; k++)
{
if (k == i)
{
continue;
}
double mag2 = b[k, i];
for (int j = i; j < n; j++)
{
b[k, j] = b[k, j] - mag2 * b[i, j];
}
for (int j = 0; j < n; j++)
{
this[k, j] = this[k, j] - mag2 * this[i, j];
}
}
}
return(this);
}
