f11mkf computes either the matrix-matrix product
, or the transposed matrix-matrix product
, according to the value of the argument
trans, where
is a real
sparse nonsymmetric matrix, of arbitrary sparsity pattern with
nonzero elements,
and
are
real dense matrices. The matrix
is stored in compressed column (Harwell–Boeing) storage format. The array
a stores all nonzero elements of
, while arrays
icolzp and
irowix store the compressed column indices and row indices of
respectively.
None.
-
1:
– Character(1)
Input
-
On entry: specifies whether or not the matrix
is transposed.
- is computed.
- is computed.
Constraint:
or .
-
2:
– Integer
Input
-
On entry: , the order of the matrix .
Constraint:
.
-
3:
– Integer
Input
-
On entry: , the number of columns of matrices and .
Constraint:
.
-
4:
– Real (Kind=nag_wp)
Input
-
On entry: , the scalar factor in the matrix multiplication.
-
5:
– Integer array
Input
-
Note: the dimension of the array
icolzp
must be at least
.
On entry: the new column index array of sparse matrix
. See
Section 2.1.3 in the
F11 Chapter Introduction.
-
6:
– Integer array
Input
-
Note: the dimension of the array
irowix
must be at least
, the number of nonzeros of the sparse matrix
.
On entry: the row index array of sparse matrix
. See
Section 2.1.3 in the
F11 Chapter Introduction.
-
7:
– Real (Kind=nag_wp) array
Input
-
Note: the dimension of the array
a
must be at least
, the number of nonzeros of the sparse matrix
.
On entry: the array of nonzero values in the sparse matrix .
-
8:
– Real (Kind=nag_wp) array
Input
-
Note: the second dimension of the array
b
must be at least
.
On entry: the matrix .
-
9:
– Integer
Input
-
On entry: the first dimension of the array
b as declared in the (sub)program from which
f11mkf is called.
Constraint:
.
-
10:
– Real (Kind=nag_wp)
Input
-
On entry: the scalar factor .
-
11:
– Real (Kind=nag_wp) array
Input/Output
-
Note: the second dimension of the array
c
must be at least
.
On entry: the matrix .
On exit:
is overwritten by
or
depending on the value of
trans.
-
12:
– Integer
Input
-
On entry: the first dimension of the array
c as declared in the (sub)program from which
f11mkf is called.
Constraint:
.
-
13:
– Integer
Input/Output
-
On entry:
ifail must be set to
,
or
to set behaviour on detection of an error; these values have no effect when no error is detected.
A value of causes the printing of an error message and program execution will be halted; otherwise program execution continues. A value of means that an error message is printed while a value of means that it is not.
If halting is not appropriate, the value
or
is recommended. If message printing is undesirable, then the value
is recommended. Otherwise, the value
is recommended.
When the value or is used it is essential to test the value of ifail on exit.
On exit:
unless the routine detects an error or a warning has been flagged (see
Section 6).
If on entry
or
, explanatory error messages are output on the current error message unit (as defined by
x04aaf).
Not applicable.
Background information to multithreading can be found in the
Multithreading documentation.
Please consult the
X06 Chapter Introduction for information on how to control and interrogate the OpenMP environment used within this routine. Please also consult the
Users' Note for your implementation for any additional implementation-specific information.
None.
This example reads in a sparse matrix
and a dense matrix
. It then calls
f11mkf to compute the matrix-matrix product
and the transposed matrix-matrix product
, where