NAG Library Function Document

nag_bessel_k1_scaled_vector (s18crc)

1  Purpose

2  Specification

3  Description

4  References

5  Arguments

1:     n – IntegerInput

On entry: $n$, the number of points.

Constraint: $\mathbf{n}\ge 0$.

2:     x[n] – const doubleInput

On entry: the argument $x_{\mathit{i}}$ of the function, for $\mathit{i}=1,2,\dots ,\mathbf{n}$.

Constraint: $\mathbf{x}\left[\mathit{i}-1\right]>0.0$, for $\mathit{i}=1,2,\dots ,\mathbf{n}$.

3:     f[n] – doubleOutput

On exit: $e^{x_i}{K}_1\left(x_i\right)$, the function values.

4:     ivalid[n] – IntegerOutput

On exit: $\mathbf{ivalid}\left[\mathit{i}-1\right]$ contains the error code for $x_{\mathit{i}}$, for $\mathit{i}=1,2,\dots ,\mathbf{n}$.

$\mathbf{ivalid}\left[i-1\right]=0$

No error.

$\mathbf{ivalid}\left[i-1\right]=1$

On entry,

$x_i\le 0.0$, $K_1\left(x_i\right)$ is undefined. $\mathbf{f}\left[\mathit{i}-1\right]$ contains $0.0$.

$\mathbf{ivalid}\left[i-1\right]=2$

$x_i$ is too close to zero, as determined by the value of the safe-range parameter nag_real_safe_small_number (X02AMC): there is a danger of causing overflow. $\mathbf{f}\left[\mathit{i}-1\right]$ contains the reciprocal of the safe-range parameter.

5:     fail – NagError *Input/Output

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

6  Error Indicators and Warnings

NE_BAD_PARAM

On entry, argument $⟨\mathit{\text{value}}⟩$ had an illegal value.

NE_INT

On entry, $\mathbf{n}=⟨\mathit{\text{value}}⟩$.
Constraint: $\mathbf{n}\ge 0$.

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.

NW_IVALID

On entry, at least one value of x was invalid.
Check ivalid for more information.

7  Accuracy

8  Parallelism and Performance

9  Further Comments

10  Example

10.1  Program Text

Program Text (s18crce.c)

10.2  Program Data

Program Data (s18crce.d)

10.3  Program Results

Program Results (s18crce.r)