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◆ CsrDussv()
| Sub CsrDussv |
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Uplo As |
String, |
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Trans As |
String, |
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Diag As |
String, |
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N As |
Long, |
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Val() As |
Double, |
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Rowptr() As |
Long, |
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Colind() As |
Long, |
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X() As |
Double, |
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Optional Info As |
Long, |
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Optional Base As |
Long = -1, |
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Optional IncX As |
Long = 1, |
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Optional Omega As |
Double = 1 |
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Solution of Ax = b or ATx = b (triangular matrices) (CSR)
- Purpose
- This routine solves one of the following systems of equations for a sparse matrix in CSR format. where b and x are n element vectors and A is an N x N upper or lower sparse triangular matrix.
- Parameters
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| [in] | Uplo | Specifies whether the matrix is an upper or lower triangular matrix as follows:
= "U": A is an upper triangular matrix.
= "L": A is an lower triangular matrix.
The other triangular elements (not including diagonal elements) are ignored. |
| [in] | Trans | Specifies the equation to be solved as follows:
= "N": A*x = b.
= "T" or "C": A^T*x = b. |
| [in] | Diag | Specifies whether or not A is assumed to be unit triangular.
= "N": A is not assumed to be unit triangular.
= "U": A is assumed to be unit triangular. (diagonal elements are assumed to be ones. Elements of Val() at diagonal element positions (if exist) are ignored.) |
| [in] | N | Number of rows and columns of matrix A. (N >= 0) (If N = 0, returns without computation) |
| [in] | Val() | Array Val(LVal - 1) (LVal >= Nnz) (Nnz is the number of nonzero elements of matrix A)
Values of nonzero elements of matrix A. |
| [in] | Rowptr() | Array Rowptr(LRowptr - 1) (LRowptr >= N + 1)
Row pointers of matrix A. |
| [in] | Colind() | Array Colind(LColind - 1) (LColind >= Nnz)
Column indices of matrix A. |
| [in,out] | X() | Array X(LX - 1) (LX >= 1 + (N - 1)*|IncX|)
[in] Right-hand side vector b.
[out] Solution vector x. |
| [out] | Info | (Optional)
= 0: Successful exit.
= i < 0: The (-i)-th argument is invalid. = i > 0: The matrix is singular (i-th diagonal element is zero). |
| [in] | Base | (Optional)
Indexing of Rowptr() and Colind().
= 0: Zero-based (C style) indexing: Starting index is 0.
= 1: One-based (Fortran style) indexing: Starting index is 1.
(default: Assumes 1 if Rowptr(0) = 1, 0 otherwise) |
| [in] | IncX | (Optional)
Storage spacing between elements of X(). (IncX <> 0) (default = 1) |
| [in] | Omega | (Optional)
ω parameter. (0 < Omega < 2) (default = 1)
if ω <> 1 then Uplo, Trans and Diag are ignored and (D/ω + L)*x = b is solved. This option is provided to use with SOR solver. |
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1.9.7