NAG CL Interface
d02pjc (ivp_​rk_​interp_​eval)

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

1: $\mathbf{icheck}$ – Nag_Boolean Input

On entry: indicates whether consistency checks on input arguments should be performed

$\mathbf{icheck}=\mathrm{Nag\_FALSE}$

Don't perform checks on input arguments.

$\mathbf{icheck}=\mathrm{Nag\_TRUE}$

Perform consistency checks on input arguments.

It is recommended to use $\mathbf{icheck}=\mathrm{Nag\_TRUE}$ on the first call following a call to d02phc and to set $\mathbf{icheck}=\mathrm{Nag\_FALSE}$ on subsequent calls within the last step to avoid the overhead of argument checking.

2: $\mathbf{n}$ – Integer Input

On entry: $n$, the dimension of the system of ODEs being integrated.

Constraint: this must be the same value as supplied in a previous call to d02pqc.

3: $\mathbf{nwant}$ – Integer Input

On entry: only the first nwant system components to be computed. This should be the same value as passed to d02phc when computing the interpolant.

Constraint: $\mathbf{nwant}=\mathbf{nwant}$ passed to d02phc.

4: $\mathbf{t}$ – double Input

On entry: $t$, the value of the independent variable where a solution is desired. Although any value of $t$ can be supplied, accurate solutions can only be obtained for values in the range of the last time-step taken by d02pgc.

5: $\mathbf{ideriv}$ – Integer Input

On entry:

$\mathbf{ideriv}=0$

Compute approximations to the first nwant components of the solution $y\left(t\right)$.

$\mathbf{ideriv}=1$

Compute approximations to the first nwant components of the first derivatives of the solution $y^{\prime }\left(t\right)$.

Constraint: $\mathbf{ideriv}=0$ or $1$.

6: $\mathbf{sol}\left[\mathbf{nwant}\right]$ – double Output

On exit:

$\mathbf{ideriv}=0$

The first nwant components of the solution $y\left(t\right)$.

$\mathbf{ideriv}=1$

The first nwant components of the first derivatives of the solution $y^{\prime }\left(t\right)$.

7: $\mathbf{wcomm}\left[\mathbf{lwcomm}\right]$ – double Communication Array

On entry: this must be the same array supplied in a previous call to d02phc. It must remain unchanged between calls.

8: $\mathbf{lwcomm}$ – Integer Input

On entry: length of wcomm. This should be the same value as supplied in a previous call to d02phc.

If in a previous call to d02pqc:

• $\mathbf{method}=\mathrm{Nag\_RK\_2\_3}$, lwcomm must be at least $1$.
• $\mathbf{method}=\mathrm{Nag\_RK\_4\_5}$, lwcomm must be at least $\mathbf{n}+\max \left(\mathbf{n},5\times \mathbf{nwant}\right)$.
• $\mathbf{method}=\mathrm{Nag\_RK\_7\_8}$, $\mathbf{lwcomm}\ge 8\times \mathbf{nwant}$.

9: $\mathbf{iwsav}\left[130\right]$ – Integer Communication Array

10: $\mathbf{rwsav}\left[32\times \mathbf{n}+350\right]$ – double Communication Array

On entry: these must be the same arrays supplied in a previous call d02pgc. They must remain unchanged between calls.

On exit: information about the integration for use on subsequent calls to d02pgc, d02phc or other associated functions.

11: $\mathbf{fail}$ – NagError * Input/Output

The NAG error argument (see Section 7 in the Introduction to the NAG Library CL Interface).

6 Error Indicators and Warnings

NE_ALLOC_FAIL

Dynamic memory allocation failed.
See Section 3.1.2 in the Introduction to the NAG Library CL Interface for further information.

NE_BAD_PARAM

On entry, argument $〈\mathit{\text{value}}〉$ had an illegal value.

NE_INT

On entry, $\mathbf{ideriv}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{ideriv}=0$ or $1$.

On entry, $\mathbf{lwcomm}=〈\mathit{\text{value}}〉$.
Constraint: for $\mathbf{method}=\mathrm{Nag\_RK\_2\_3}$, $\mathbf{lwcomm}\ge 1$.

NE_INT_2

On entry, $\mathbf{lwcomm}=〈\mathit{\text{value}}〉$ and $\mathbf{nwant}=〈\mathit{\text{value}}〉$.
Constraint: for $\mathbf{method}=\mathrm{Nag\_RK\_7\_8}$, $\mathbf{lwcomm}\ge 8\times \mathbf{nwant}$.

NE_INT_3

On entry, $\mathbf{lwcomm}=〈\mathit{\text{value}}〉$, $\mathbf{n}=〈\mathit{\text{value}}〉$ and $\mathbf{nwant}=〈\mathit{\text{value}}〉$.
Constraint: for $\mathbf{method}=\mathrm{Nag\_RK\_4\_5}$, $\mathbf{lwcomm}\ge \mathbf{n}+\max \left(\mathbf{n},5\times \mathbf{nwant}\right)$.

NE_INT_CHANGED

On entry, $\mathbf{n}=〈\mathit{\text{value}}〉$, but the value passed to the setup routine was $\mathbf{n}=〈\mathit{\text{value}}〉$.

On entry, $\mathbf{nwant}=〈\mathit{\text{value}}〉$, but on interpolation setup $\mathbf{nwant}=〈\mathit{\text{value}}〉$.
Constraint: nwant must be unchanged from setup.

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 7.5 in the Introduction to the NAG Library CL Interface for further information.

NE_MISSING_CALL

On entry, a previous call to the setup function has not been made or the communication arrays have become corrupted, or a catastrophic error has already been detected elsewhere.
You cannot continue integrating the problem.

You cannot call this function before you have called the interpolation setup.

NE_NO_LICENCE

Your licence key may have expired or may not have been installed correctly.
See Section 8 in the Introduction to the NAG Library CL Interface for further information.

NE_PREV_CALL_INI

The previous call to the interpolation setup function returned an error.

7 Accuracy

8 Parallelism and Performance

9 Further Comments

10 Example