1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
|
///
/// This file is part of Rheolef.
///
/// Copyright (C) 2000-2009 Pierre Saramito <Pierre.Saramito@imag.fr>
///
/// Rheolef 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; either version 2 of the License, or
/// (at your option) any later version.
///
/// Rheolef 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.
///
/// You should have received a copy of the GNU General Public License
/// along with Rheolef; if not, write to the Free Software
/// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
///
/// =========================================================================
//! @examplefile lambda2alpha.h The combustion problem -- inversion of the parameter function
#include "lambda_c.h"
Float lambda2alpha (Float lambda, bool up = false) {
static const Float ac = alpha_c();
Float tol = 1e2*numeric_limits<Float>::epsilon();
size_t max_iter = 1000;
Float a_min = up ? ac : 0;
Float a_max = up ? 100 : ac;
for (size_t k = 0; abs(a_max - a_min) > tol; ++k) {
Float a1 = (a_max + a_min)/2;
Float lambda1 = 8*sqr(a1/cosh(a1));
if ((up && lambda > lambda1) || (!up && lambda < lambda1))
{ a_max = a1; }
else { a_min = a1; }
check_macro (k < max_iter, "lambda2alpha: max_iter=" << k
<< " reached and err=" << a_max - a_min);
}
return(a_max + a_min)/2;
};
|
