nag_sparse_nherm_sort (f11znc) takes a coordinate storage (CS) representation (see
Section 2.1.1 in the f11 Chapter Introduction) of a sparse
by
complex non-Hermitian matrix
, and reorders the nonzero elements by increasing row index and increasing column index within each row. Entries with duplicate row and column indices may be removed, or the values may be summed. Any entries with zero values may optionally be removed.
The function also returns a pointer array
istr to the starting address of each row in
.
None.
- 1:
– IntegerInput
-
On entry: , the order of the matrix .
Constraint:
.
- 2:
– Integer *Input/Output
-
On entry: the number of nonzero elements in the matrix .
Constraint:
.
On exit: the number of nonzero elements with unique row and column indices.
- 3:
– ComplexInput/Output
-
Note: the dimension,
dim, of the array
a
must be at least
.
On entry: the nonzero elements of the matrix . These may be in any order and there may be multiple nonzero elements with the same row and column indices.
On exit: the nonzero elements ordered by increasing row index, and by increasing column index within each row. Each nonzero element has a unique row and column index.
- 4:
– IntegerInput/Output
-
Note: the dimension,
dim, of the array
irow
must be at least
.
On entry: the row indices corresponding to the nonzero elements supplied in the array
a.
Constraint:
, for .
On exit: the first
nnz elements contain the row indices corresponding to the nonzero elements returned in the array
a.
- 5:
– IntegerInput/Output
-
Note: the dimension,
dim, of the array
icol
must be at least
.
On entry: the column indices corresponding to the nonzero elements supplied in the array
a.
Constraint:
, for .
On exit: the first
nnz elements contain the column indices corresponding to the nonzero elements returned in the array
a.
- 6:
– Nag_SparseNsym_DupsInput
-
On entry: indicates how any nonzero elements with duplicate row and column indices are to be treated.
- The entries are removed.
- The relevant values in a are summed.
- The function fails with NE_NON_ZERO_DUP on detecting a duplicate.
Constraint:
, or .
- 7:
– Nag_SparseNsym_ZerosInput
-
On entry: indicates how any elements with zero values in array
a are to be treated.
- The entries are removed.
- The entries are kept.
- The function fails with NE_ZERO_COEFF on detecting a zero.
Constraint:
, or .
- 8:
– IntegerOutput
-
On exit:
, for
, is the starting address in the arrays
a,
irow and
icol of row
of the matrix
.
is the address of the last nonzero element in
plus one.
- 9:
– NagError *Input/Output
-
The NAG error argument (see
Section 3.7 in How to Use the NAG Library and its Documentation).
- NE_ALLOC_FAIL
-
Dynamic memory allocation failed.
See
Section 2.3.1.2 in How to Use the NAG Library and its Documentation for further information.
- NE_BAD_PARAM
-
On entry, argument had an illegal value.
- NE_INT
-
On entry, .
Constraint: .
On entry, .
Constraint: .
- NE_INTERNAL_ERROR
-
An internal error has occurred in this function. Check the function call and any array sizes. If the call is correct then please contact
NAG for assistance.
See
Section 2.7.6 in How to Use the NAG Library and its Documentation for further information.
- NE_INVALID_CS
-
On entry, , and .
Constraint: and .
On entry, , and .
Constraint: and .
- NE_NO_LICENCE
-
Your licence key may have expired or may not have been installed correctly.
See
Section 2.7.5 in How to Use the NAG Library and its Documentation for further information.
- NE_NON_ZERO_DUP
-
On entry, a duplicate entry has been found in row and column : , .
- NE_ZERO_COEFF
-
On entry, a zero entry has been found in row and column : , .
Not applicable.
The time taken for a call to
nag_sparse_nherm_sort (f11znc) is proportional to
nnz.
Note that the resulting matrix may have either rows or columns with no entries. If row has no entries then .