NAG C Library Function Document

nag_ode_ivp_adams_interp (d02qzc)

1

Purpose

2

Specification

3

Description

4

References

5

Arguments

1:    $\mathbf{neqf}$ – IntegerInput

On entry: the number of differential equations.

Constraint: $\mathbf{neqf}\ge 1$.

2:    $\mathbf{twant}$ – doubleInput

On entry: the point at which components of the solution and derivative are to be evaluated. twant should not normally be an extrapolation point, that is twant should satisfy

$\mathbf{opt}\mathbf{\to }\mathbf{tcurr}-\mathbf{opt}\mathbf{\to }\mathbf{hlast}\le \mathbf{twant}\le \mathbf{opt}\mathbf{\to }\mathbf{tcurr}$.

or if integration is proceeding in the negative direction

$\mathbf{opt}\mathbf{\to }\mathbf{tcurr}-\mathbf{opt}\mathbf{\to }\mathbf{hlast}\ge \mathbf{twant}\ge \mathbf{opt}\mathbf{\to }\mathbf{tcurr}$.

Extrapolation is permitted but not recommended and a fail value of NW_EXTRAPOLATION is returned whenever extrapolation is attempted.

3:    $\mathbf{nwant}$ – IntegerInput

On entry: the number of components of the solution and derivative whose values, at twant, are required. The first nwant components are evaluated.

Constraint: $1\le \mathbf{nwant}\le \mathbf{neqf}$.

4:    $\mathbf{ywant}\left[\mathbf{nwant}\right]$ – doubleOutput

On exit: $\mathbf{ywant}\left[\mathit{i}-1\right]$ contains the calculated value of the $\mathit{i}$th component of the solution at twant, for $\mathit{i}=1,2,\dots ,\mathbf{nwant}$.

5:    $\mathbf{ypwant}\left[\mathbf{nwant}\right]$ – doubleOutput

On exit: $\mathbf{ypwant}\left[\mathit{i}-1\right]$ contains the calculated value of the $\mathit{i}$th component of the derivative at twant, for $\mathit{i}=1,2,\dots ,\mathbf{nwant}$.

6:    $\mathbf{opt}$ – Nag_ODE_Adams *Input

On entry: the structure of type Nag_ODE_Adams as output from the integration function nag_ode_ivp_adams_roots (d02qfc). The structure must be passed unchanged. (See Section 9 for comments about deallocation of memory from opt.)

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

The NAG error argument (see Section 3.7 in How to Use the NAG Library and its Documentation).

6

Error Indicators and Warnings

NE_INT_ARG_LT

On entry, $\mathbf{nwant}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{nwant}\ge 1$.

NE_NEQF

The value of neqf supplied is not the same as that given to the setup function nag_ode_ivp_adams_setup (d02qwc). $\mathbf{neqf}=〈\mathit{\text{value}}〉$ but the value given to nag_ode_ivp_adams_setup (d02qwc) was $〈\mathit{\text{value}}〉$.

NE_NO_INTEGRATE

The integrator function nag_ode_ivp_adams_roots (d02qfc) has not been called.

NE_NO_STEPS

No successful integration steps were taken in the call(s) to the integration function nag_ode_ivp_adams_roots (d02qfc).

NE_NWANT_GT

nwant is greater than the value of neqf given to the setup function nag_ode_ivp_adams_setup (d02qwc). $\mathbf{nwant}=〈\mathit{\text{value}}〉$, $\mathbf{neqf}=〈\mathit{\text{value}}〉$.

NW_EXTRAPOLATION

Extrapolation requested, $\mathbf{twant}=〈\mathit{\text{value}}〉$.

7

Accuracy

8

Parallelism and Performance

9

Further Comments

10

Example

10.1

Program Text

Program Text (d02qzce.c)

10.2

Program Data

10.3

Program Results

Program Results (d02qzce.r)