NAG FL Interface
f01ckf (real_​gen_​matmul)

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

1: $\mathbf{a}(\mathbf{n},\mathbf{p})$ – Real (Kind=nag_wp) array Output

On exit: if $\mathbf{opt}=1$, a contains the result of the matrix multiplication.

2: $\mathbf{b}(\mathbf{n},\mathbf{m})$ – Real (Kind=nag_wp) array Input/Output

On entry: the $n\times m$ matrix $B$.

On exit: if $\mathbf{opt}=2$, b contains the result of the multiplication.

3: $\mathbf{c}(\mathbf{m},\mathbf{p})$ – Real (Kind=nag_wp) array Input/Output

On entry: the $m\times p$ matrix $C$.

On exit: if $\mathbf{opt}=3$, c contains the result of the multiplication.

4: $\mathbf{n}$ – Integer Input

On entry: $n$, the number of rows of the array $A$ and of the array $B$.

Constraints:

• if $\mathbf{opt}=3$, $\mathbf{n}=\mathbf{m}$;
• otherwise $\mathbf{n}\ge 1$.

5: $\mathbf{p}$ – Integer Input

On entry: $p$, the number of columns of the array $A$ and of the array $C$.

Constraints:

• if $\mathbf{opt}=2$, $\mathbf{p}=\mathbf{m}$;
• otherwise $\mathbf{p}\ge 1$.

6: $\mathbf{m}$ – Integer Input

On entry: $m$, the number of columns of the array $B$ and rows of the array $C$.

Constraints:

• if $\mathbf{opt}=2$, $\mathbf{m}=\mathbf{p}$;
• if $\mathbf{opt}=3$, $\mathbf{m}=\mathbf{n}$;
• if $\mathbf{opt}\ne 1$, $\mathbf{m}\le \mathbf{iz}$;
• otherwise $\mathbf{m}\ge 1$.

7: $\mathbf{z}\left(\mathbf{iz}\right)$ – Real (Kind=nag_wp) array Workspace

8: $\mathbf{iz}$ – Integer Input

On entry: the dimension of the array z as declared in the (sub)program from which f01ckf is called.

Constraints:

• if $\mathbf{opt}=1$, $\mathbf{iz}\ge 1$;
• if $\mathbf{opt}\ne 1$, $\mathbf{iz}\ge \mathbf{m}$.

9: $\mathbf{opt}$ – Integer Input

On entry: the value of opt determines which array is to contain the final result.

$\mathbf{opt}=1$

a must be distinct from b and c and, on exit, contains the result. b and c need not be distinct in this case.

$\mathbf{opt}=2$

b must be distinct from c and on exit, contains the result. a is not used in this case and need not be distinct from b or c.

$\mathbf{opt}=3$

c must be distinct from b and on exit, contains the result. a is not used in this case and need not be distinct from b or c.

Constraint: $1\le \mathbf{opt}\le 3$.

10: $\mathbf{ifail}$ – Integer Input/Output

On entry: ifail must be set to $0$, $\mathrm{-1}$ or $1$ to set behaviour on detection of an error; these values have no effect when no error is detected.

A value of $0$ causes the printing of an error message and program execution will be halted; otherwise program execution continues. A value of $\mathrm{-1}$ means that an error message is printed while a value of $1$ means that it is not.

If halting is not appropriate, the value $\mathrm{-1}$ or $1$ is recommended. If message printing is undesirable, then the value $1$ is recommended. Otherwise, the value $0$ is recommended. When the value $-\mathbf{1}$ or $\mathbf{1}$ is used it is essential to test the value of ifail on exit.

On exit: $\mathbf{ifail}=\mathbf{0}$ unless the routine detects an error or a warning has been flagged (see Section 6).

6 Error Indicators and Warnings

$\mathbf{ifail}=1$

On entry, $\mathbf{m}=⟨\mathit{\text{value}}⟩$.
Constraint: $\mathbf{m}\ge 1$.

On entry, $\mathbf{n}=⟨\mathit{\text{value}}⟩$.
Constraint: $\mathbf{n}\ge 1$.

On entry, $\mathbf{p}=⟨\mathit{\text{value}}⟩$.
Constraint: $\mathbf{p}\ge 1$.

$\mathbf{ifail}=2$

On entry, $\mathbf{m}=⟨\mathit{\text{value}}⟩$ and $\mathbf{p}=⟨\mathit{\text{value}}⟩$.
Constraint: if $\mathbf{opt}=2$, $\mathbf{m}=\mathbf{p}$.

$\mathbf{ifail}=3$

On entry, $\mathbf{n}=⟨\mathit{\text{value}}⟩$ and $\mathbf{m}=⟨\mathit{\text{value}}⟩$.
Constraint: if $\mathbf{opt}=3$, $\mathbf{n}=\mathbf{m}$.

$\mathbf{ifail}=4$

On entry, $\mathbf{opt}=⟨\mathit{\text{value}}⟩$, $\mathbf{iz}=⟨\mathit{\text{value}}⟩$ and $\mathbf{m}=⟨\mathit{\text{value}}⟩$.
Constraint: if $\mathbf{opt}\ne 1$, $\mathbf{iz}\ge \mathbf{m}$.

$\mathbf{ifail}=-99$

An unexpected error has been triggered by this routine. Please contact NAG.

See Section 7 in the Introduction to the NAG Library FL Interface for further information.

$\mathbf{ifail}=-399$

Your licence key may have expired or may not have been installed correctly.

See Section 8 in the Introduction to the NAG Library FL Interface for further information.

$\mathbf{ifail}=-999$

Dynamic memory allocation failed.

See Section 9 in the Introduction to the NAG Library FL Interface for further information.

7 Accuracy

8 Parallelism and Performance

9 Further Comments

10 Example

10.1 Program Text

10.2 Program Data

10.3 Program Results