/usr/include/expintegrals.h is in libalglib-dev 2.6.0-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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Cephes Math Library Release 2.8: June, 2000
Copyright by Stephen L. Moshier
Contributors:
* Sergey Bochkanov (ALGLIB project). Translation from C to
pseudocode.
See subroutines comments for additional copyrights.
>>> SOURCE LICENSE >>>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation (www.fsf.org); either version 2 of the
License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
A copy of the GNU General Public License is available at
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>>> END OF LICENSE >>>
*************************************************************************/
#ifndef _expintegrals_h
#define _expintegrals_h
#include "ap.h"
#include "ialglib.h"
/*************************************************************************
Exponential integral Ei(x)
x
- t
| | e
Ei(x) = -|- --- dt .
| | t
-
-inf
Not defined for x <= 0.
See also expn.c.
ACCURACY:
Relative error:
arithmetic domain # trials peak rms
IEEE 0,100 50000 8.6e-16 1.3e-16
Cephes Math Library Release 2.8: May, 1999
Copyright 1999 by Stephen L. Moshier
*************************************************************************/
double exponentialintegralei(double x);
/*************************************************************************
Exponential integral En(x)
Evaluates the exponential integral
inf.
-
| | -xt
| e
E (x) = | ---- dt.
n | n
| | t
-
1
Both n and x must be nonnegative.
The routine employs either a power series, a continued
fraction, or an asymptotic formula depending on the
relative values of n and x.
ACCURACY:
Relative error:
arithmetic domain # trials peak rms
IEEE 0, 30 10000 1.7e-15 3.6e-16
Cephes Math Library Release 2.8: June, 2000
Copyright 1985, 2000 by Stephen L. Moshier
*************************************************************************/
double exponentialintegralen(double x, int n);
#endif
|