NAG Library Manual, Mark 26
NAG AD Library Manual, Mark 26
NAG C Library Manual, Mark 26
G01 (stat) Chapter Contents
G01 (stat) Chapter Introduction
NAG Library Routine Document
g01qtf (pdf_landau_moment2)
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NAG Library Manual, Mark 26
NAG AD Library Manual, Mark 26
NAG C Library Manual, Mark 26
G01 (stat) Chapter Contents
G01 (stat) Chapter Introduction
▸
▿
Contents
1
Purpose
2
Specification
3
Description
4
References
5
Arguments
6
Error Indicators and Warnings
7
Accuracy
8
Parallelism and Performance
9
Further Comments
▸
▿
10
Example
10.1
Program Text
10.2
Program Data
10.3
Program Results
© The Numerical Algorithms Group Ltd. 2018
1
Purpose
g01qtf
returns the value of the second moment
Φ
2
x
of the Landau density function.
2
Specification
Fortran Interface
Function g01qtf (
x
)
Real (Kind=nag_wp)
::
g01qtf
Real (Kind=nag_wp), Intent (In)
::
x
C Header Interface
#include <nagmk26.h>
double
g01qtf_ (
const double *
x
)
3
Description
g01qtf
evaluates an approximation to the second moment
Φ
2
x
of the Landau density function given by
Φ
2
x
=
1
Φ
x
∫
-
∞
x
λ
2
ϕ
λ
d
λ
,
where
ϕ
λ
is described in
g01mtf
, using piecewise approximation by rational functions. Further details can be found in
Kölbig and Schorr (1984)
.
To obtain the value of
Φ
1
x
,
g01ptf
can be used.
4
References
Kölbig K S and Schorr B (1984) A program package for the Landau distribution
Comp. Phys. Comm.
31
97–111
5
Arguments
1:
x
– Real (Kind=nag_wp)
Input
On entry
: the argument
x
of the function.
6
Error Indicators and Warnings
None.
7
Accuracy
At least
7
significant digits are usually correct, but occasionally only
6
. Such accuracy is normally considered to be adequate for applications in experimental physics.
8
Parallelism and Performance
g01qtf
is not threaded in any implementation.
9
Further Comments
None.
10
Example
This example evaluates
Φ
2
x
at
x
=
0.5
, and prints the results.
10.1
Program Text
Program Text (g01qtfe.f90)
10.2
Program Data
Program Data (g01qtfe.d)
10.3
Program Results
Program Results (g01qtfe.r)
NAG Library Manual, Mark 26
NAG AD Library Manual, Mark 26
NAG C Library Manual, Mark 26
G01 (stat) Chapter Contents
G01 (stat) Chapter Introduction
© The Numerical Algorithms Group Ltd. 2018