/// <summary>
/// Solve the generalized eigenvalue problem in user-defined shift-invert mode.
/// </summary>
public IEigenSolverResult SolveGeneralized(int k, double sigma, ShiftMode mode, Spectrum job = Spectrum.LargestMagnitude)
{
if (!symmetric && !(mode == ShiftMode.None || mode == ShiftMode.Regular))
{
throw new InvalidOperationException("This mode is only available for symmetric eigenvalue problems.");
}
if (!CheckSquare(A))
{
throw new InvalidOperationException("Cannot solve eigenvalue problem with non-square matrix.");
}
if (!Job.Validate(symmetric, job))
{
throw new ArgumentException("Invalid job for symmetric eigenvalue problem.", "job");
}
var result = new ArpackResult(k, size, ComputeEigenVectors, symmetric);
var handles = new List <GCHandle>();
var a = GetMatrix(A, handles);
var b = GetMatrix(B, handles);
var e = result.GetEigenvalueStorage(handles);
int conv = 0;
if (symmetric)
{
char m = 'S';
if (mode == ShiftMode.Buckling)
{
m = 'B';
}
else if (mode == ShiftMode.Cayley)
{
m = 'C';
}
conv = NativeMethods.ar_di_sg_shift(GetJob(job), m, k, ArnoldiCount, Iterations,
Tolerance, sigma, ref a, ref b, ref e);
}
else
{
conv = NativeMethods.ar_di_ng_shift(GetJob(job), k, ArnoldiCount, Iterations,
Tolerance, sigma, ref a, ref b, ref e);
}
result.IterationsTaken = e.iterations;
result.ArnoldiCount = e.ncv;
result.ConvergedEigenValues = conv;
result.ErrorCode = e.info;
InteropHelper.Free(handles);
return(result);
}
/// <summary>
/// Special case solving the standard real generalized eigenvalue problem with complex shift.
/// </summary>
/// <param name="k">The number of eigenvalues to compute.</param>
/// <param name="sigma_r">The real part of the complex shift.</param>
/// <param name="sigma_i">The imaginary part of the complex shift.</param>
/// <param name="part">Part to apply ('R' for real, 'I' for imaginary).</param>
/// <param name="job">The part of the spectrum to compute.</param>
/// <returns>The number of converged eigenvalues.</returns>
public IEigenSolverResult SolveGeneralized(int k, double sigma_r, double sigma_i, char part, Spectrum job = Spectrum.LargestMagnitude)
{
if (symmetric)
{
throw new InvalidOperationException("Complex shift doesn't apply to real symmetric eigenvalue problems.");
}
if (!CheckSquare(A))
{
throw new InvalidOperationException("Cannot solve eigenvalue problem with non-square matrix.");
}
if (!Job.ValidateGeneral(job))
{
throw new ArgumentException("Invalid job for non-symmetric eigenvalue problem.", "job");
}
part = char.ToUpperInvariant(part);
if (part != 'R' && part != 'I')
{
throw new ArgumentException("Invalid part specified for complex shift.", "part");
}
var result = new ArpackResult(k, size, ComputeEigenVectors, symmetric);
var handles = new List <GCHandle>();
var a = GetMatrix(A, handles);
var b = GetMatrix(B, handles);
var e = result.GetEigenvalueStorage(handles);
int conv = 0;
conv = NativeMethods.ar_di_ng_shift_cx(GetJob(job),
k, ArnoldiCount, Iterations, Tolerance,
part, sigma_r, sigma_i, ref a, ref b, ref e);
result.IterationsTaken = e.iterations;
result.ArnoldiCount = e.ncv;
result.ConvergedEigenValues = conv;
result.ErrorCode = e.info;
InteropHelper.Free(handles);
return(result);
}
/// <summary>
/// Compute singular values and the partial singular value decomposition.
/// </summary>
/// <param name="k">The number of singular values to compute.</param>
/// <param name="normal">Use normal equation to compute (squared) singular values.</param>
/// <param name="job">The part of the spectrum to compute.</param>
/// <returns>The number of converged singular values.</returns>
/// <remarks>
/// If <paramref name="normal"/> is true, the normal equation <c>(A'*A)*v = sigma*v</c>
/// is considered, where A is an m-by-n real matrix. This formulation is appropriate
/// when m >= n. The roles of A and A' must be reversed in the case that m < n.
///
/// The eigenvalues returned are the squared singular values of A. If requested, the
/// returned eigenvectors correspond to the right singular vectors, if <c>A = U*S*V'</c>.
/// The left singular vectors can be computed from the equation <c>A*v - sigma*u = 0</c>.
///
/// If <paramref name="normal"/> is false, the symmetric system <c>[0 A; A' 0]</c> is
/// considered (size m + n), where A is an m-by-n real matrix.
///
/// This problem can be used to obtain the decomposition <c>A = U*S*V'</c>. The positive
/// eigenvalues of this problem are the singular values of A (the eigenvalues come in
/// pairs, the negative eigenvalues have the same magnitude of the positive ones and
/// can be discarded). The columns of U can be extracted from the first m components
/// of the eigenvectors y, while the columns of V can be extracted from the remaining
/// n components.
/// </remarks>
public IEigenSolverResult SingularValues(int k, bool normal, Spectrum job = Spectrum.LargestMagnitude)
{
if (!Job.ValidateSymmetric(job))
{
throw new ArgumentException("Invalid job for singular value decomposition.", "job");
}
int m = A.RowCount;
int n = A.ColumnCount;
if (normal && m < n)
{
throw new InvalidOperationException("Number of columns must not be smaller than number of rows (use transposed matrix).");
}
int size = normal ? n : m + n;
var result = new ArpackResult(k, size, ComputeEigenVectors, true);
var handles = new List <GCHandle>();
var a = GetMatrix(A, handles);
var e = result.GetEigenvalueStorage(handles);
int conv = 0;
if (normal)
{
conv = NativeMethods.ar_di_svd_nrm(GetJob(job),
k, ArnoldiCount, Iterations, Tolerance, ref a, ref e);
}
else
{
conv = NativeMethods.ar_di_svd(GetJob(job),
k, ArnoldiCount, Iterations, Tolerance, ref a, ref e);
}
result.IterationsTaken = e.iterations;
result.ArnoldiCount = e.ncv;
result.ConvergedEigenValues = conv;
result.ErrorCode = e.info;
InteropHelper.Free(handles);
return(result);
}
/// <summary>
/// Solve the generalized eigenvalue problem.
/// </summary>
public override IEigenSolverResult SolveGeneralized(int k, Spectrum job)
{
if (!CheckSquare(A))
{
throw new InvalidOperationException("Cannot solve eigenvalue problem with non-square matrix.");
}
if (!Job.Validate(symmetric, job))
{
throw new ArgumentException("Invalid job for given eigenvalue problem.", "job");
}
var result = new ArpackResult(k, size, ComputeEigenVectors, symmetric);
var handles = new List <GCHandle>();
var a = GetMatrix(A, handles);
var b = GetMatrix(B, handles);
var e = result.GetEigenvalueStorage(handles);
int conv = 0;
if (symmetric)
{
conv = NativeMethods.ar_di_sg(GetJob(job), k, ArnoldiCount,
Iterations, Tolerance, ref a, ref b, ref e);
}
else
{
conv = NativeMethods.ar_di_ng(GetJob(job), k, ArnoldiCount,
Iterations, Tolerance, ref a, ref b, ref e);
}
result.IterationsTaken = e.iterations;
result.ArnoldiCount = e.ncv;
result.ConvergedEigenValues = conv;
result.ErrorCode = e.info;
InteropHelper.Free(handles);
return(result);
}
