NAG Library Function Document

nag_ode_ivp_adams_interp (d02qzc)

1  Purpose

2  Specification

3  Description

4  References

5  Arguments

1:     neqf – IntegerInput

On entry: the number of differential equations.

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

2:     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:     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:     ywant[nwant] – 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:     ypwant[nwant] – 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:     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:     fail – NagError *Input/Output

The NAG error argument (see Section 3.6 in the Essential Introduction).

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)