/// <summary>
/// generalized multiplication, triple product.
/// </summary>
public void Multiply(double scale, MultidimensionalArray A, MultidimensionalArray B, MultidimensionalArray C, double thisscale, string Tindex, string Aindex, string Bindex, string Cindex)
{
// check arguments
// ===============
if (Tindex.Length != this.Dimension)
{
throw new ArgumentException();
}
if (Aindex.Length != A.Dimension)
{
throw new ArgumentException();
}
if (Bindex.Length != B.Dimension)
{
throw new ArgumentException();
}
if (Cindex.Length != C.Dimension)
{
throw new ArgumentException();
}
// determine indices for intermediate result
// =========================================
var _Aindex = Aindex.ToCharArray();
var _Bindex = Bindex.ToCharArray();
var _Cindex = Cindex.ToCharArray();
var _Tindex = Tindex.ToCharArray();
List <char> _Qindex = new List <char>();
List <int> _Qlength = new List <int>();
for (int i = 0; i < _Aindex.Length; i++)
{
char g = _Aindex[i];
int L = A.GetLength(i);
if (Array.IndexOf <char>(_Tindex, g) >= 0 || Array.IndexOf <char>(_Cindex, g) >= 0)
{
_Qindex.Add(g);
_Qlength.Add(L);
}
}
for (int i = 0; i < _Bindex.Length; i++)
{
char g = _Bindex[i];
int L = B.GetLength(i);
if (!_Qindex.Contains(g))
{
if (Array.IndexOf <char>(_Tindex, g) >= 0 || Array.IndexOf <char>(_Cindex, g) >= 0)
{
_Qindex.Add(g);
_Qlength.Add(L);
}
}
}
// execute multiplication
// ======================
// Q = A*B
//var Q = MultidimensionalArray.Create(_Qlength.ToArray());
int iBuf;
var Q = TempBuffer.GetTempMultidimensionalarray(out iBuf, _Qlength.ToArray());
string Qindex = new string(_Qindex.ToArray());
Q.Multiply(1.0, A, B, 0.0, Qindex, Aindex, Bindex);
// this = scale*Q*C + this*thisscale
this.Multiply(scale, Q, C, thisscale, Tindex, Qindex, Cindex);
TempBuffer.FreeTempBuffer(iBuf);
}
static (double[] EigenVals, MultidimensionalArray EigenVect) EigenspaceSymmInternal(this IMatrix Inp, bool ComputeVectors)
{
if (Inp.NoOfCols != Inp.NoOfRows)
{
throw new ArgumentException("Not supported for non-symmetrical matrices.");
}
int N = Inp.NoOfRows;
int JOBZ = ComputeVectors ? 'V' : 'N';
// 'N': Compute eigenvalues only;
// 'V': Compute eigenvalues and eigenvectors.
int UPLO = 'L';
// 'U': Upper triangle of A is stored;
// 'L': Lower triangle of A is stored.
unsafe {
double[] InpBuffer = TempBuffer.GetTempBuffer(out int RefInp, N * N);
double[] Eigis = new double[N];
MultidimensionalArray EigiVect = ComputeVectors ? MultidimensionalArray.Create(N, N) : null;
fixed(double *pInp = InpBuffer, pEigis = Eigis)
{
CopyToUnsafeBuffer(Inp, pInp, true);
int LDA = N;
int info;
// phase 1: work size estimation
double WorkSize;
int LWORK = -1; // triggers estimation
LAPACK.F77_LAPACK.DSYEV_(ref JOBZ, ref UPLO, ref N, pInp, ref LDA, pEigis, &WorkSize, ref LWORK, out info);
if (info != 0)
{
TempBuffer.FreeTempBuffer(RefInp);
throw new ArithmeticException("LAPACK DSYEV (symmetrical matrix eigenvalues) returned info " + info);
}
LWORK = (int)WorkSize;
// phase 2: computation
double[] WorkBuffer = TempBuffer.GetTempBuffer(out int RefWork, LWORK * 1);
fixed(double *pWork = WorkBuffer)
{
LAPACK.F77_LAPACK.DSYEV_(ref JOBZ, ref UPLO, ref N, pInp, ref LDA, pEigis, pWork, ref LWORK, out info);
TempBuffer.FreeTempBuffer(RefWork);
if (info != 0)
{
TempBuffer.FreeTempBuffer(RefInp);
throw new ArithmeticException("LAPACK DSYEV (symmetrical matrix eigenvalues) returned info " + info);
}
if (EigiVect != null)
{
CopyFromUnsafeBuffer(EigiVect, pInp, true);
}
}
}
TempBuffer.FreeTempBuffer(RefInp);
return(Eigis, EigiVect);
}
}
