NAG FL Interface
d02ucf (bvp_​ps_​lin_​cgl_​grid)

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

1: $\mathbf{n}$ – Integer Input

On entry: $n$, where the number of grid points is $n+1$. This is also the largest order of Chebyshev polynomial in the Chebyshev series to be computed.

Constraint: $\mathbf{n}>0$ and n is even.

2: $\mathbf{a}$ – Real (Kind=nag_wp) Input

On entry: $a$, the lower bound of domain $\left[a,b\right]$.

Constraint: $\mathbf{a}<\mathbf{b}$.

3: $\mathbf{b}$ – Real (Kind=nag_wp) Input

On entry: $b$, the upper bound of domain $\left[a,b\right]$.

Constraint: $\mathbf{b}>\mathbf{a}$.

4: $\mathbf{x}\left(\mathbf{n}+1\right)$ – Real (Kind=nag_wp) array Output

On exit: the Chebyshev Gauss–Lobatto grid points, $x_{\mathit{i}}$, for $\mathit{i}=1,2,\dots ,n+1$, on $\left[a,b\right]$.

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

On entry: ifail must be set to $0$, $-1\text{ or }1$. If you are unfamiliar with this argument you should refer to Section 4 in the Introduction to the NAG Library FL Interface for details.

For environments where it might be inappropriate to halt program execution when an error is detected, the value $-1\text{ or }1$ is recommended. If the output of error messages is undesirable, then the value $1$ is recommended. Otherwise, if you are not familiar with this argument, the recommended value is $0$. When the value $-\mathbf{1}\text{ or }\mathbf{1}$ 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, $\mathbf{n}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{n}>0$.

On entry, $\mathbf{n}=〈\mathit{\text{value}}〉$.
Constraint: n is even.

$\mathbf{ifail}=2$

On entry, $\mathbf{a}=〈\mathit{\text{value}}〉$ and $\mathbf{b}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{a}<\mathbf{b}$.

$\mathbf{ifail}=-99$

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