NAG C Library Function Document

nag_bessel_j_alpha (s18ekc)

1

Purpose

2

Specification

3

Description

4

References

5

Arguments

1:    $\mathbf{x}$ – doubleInput

On entry: the argument $x$ of the function.

Constraint: if $\mathbf{nl}<0$, $\mathbf{x}\ne 0.0$.

2:    $\mathbf{a}$ – doubleInput

On entry: the order $\alpha$ of the first member in the required sequence of function values.

Constraint: $0.0\le \mathbf{a}<1.0$.

3:    $\mathbf{nl}$ – IntegerInput

On entry: the value of $N$.

Constraint: $\mathrm{abs}\left(\mathbf{nl}\right)\le 101$.

4:    $\mathbf{b}[\times ]$ – ComplexOutput

On exit: with $\mathbf{fail}\mathbf{.}\mathbf{code}=\mathrm{NE\_NOERROR}$ or $\mathbf{fail}\mathbf{.}\mathbf{code}=\mathbf{NW\_SOME\_PRECISION\_LOSS}$, the required sequence of function values: b$\left(\mathit{n}\right)$ contains $J_{\alpha +\mathit{n}-1}\left(x\right)$ if $\mathbf{nl}\ge 0$ and $J_{\alpha -\mathit{n}+1}\left(x\right)$ otherwise, for $\mathit{n}=1,2,\dots ,\mathrm{abs}\left(\mathbf{nl}\right)+1$.

5:    $\mathbf{fail}$ – 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

On entry, $\mathbf{nl}=〈\mathit{\text{value}}〉$.
Constraint: $\mathrm{abs}\left(\mathbf{nl}\right)\le 101$.

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.

NE_OVERFLOW_LIKELY

The evaluation has been abandoned due to the likelihood of overflow.

NE_REAL

On entry, $\mathbf{a}=〈\mathit{\text{value}}〉$.
Constraint: $0.0\le \mathbf{a}<1.0$.

NE_REAL_INT

On entry, $\mathbf{x}=〈\mathit{\text{value}}〉$, $\mathbf{nl}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{x}\ne 0.0$ when $\mathbf{nl}<0$.

NE_TERMINATION_FAILURE

The evaluation has been abandoned due to failure to satisfy the termination condition.

NE_TOTAL_PRECISION_LOSS

The evaluation has been abandoned due to total loss of precision.

NW_SOME_PRECISION_LOSS

The evaluation has been completed but some precision has been lost.

7

Accuracy

8

Parallelism and Performance

9

Further Comments

10

Example

10.1

Program Text

Program Text (s18ekce.c)

10.2

Program Data

Program Data (s18ekce.d)

10.3

Program Results

Program Results (s18ekce.r)