/usr/include/dolfin/math/Lagrange.h is in libdolfin1.0-dev 1.0.0-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 | // Copyright (C) 2003-2005 Anders Logg
//
// This file is part of DOLFIN.
//
// DOLFIN is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// DOLFIN 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 Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with DOLFIN. If not, see <http://www.gnu.org/licenses/>.
//
// First added: 2003-06-12
// Last changed: 2009-09-08
#ifndef __LAGRANGE_H
#define __LAGRANGE_H
#include <vector>
#include <dolfin/log/Event.h>
#include <dolfin/common/types.h>
#include <dolfin/common/Variable.h>
namespace dolfin
{
/// Lagrange polynomial (basis) with given degree q determined by n = q + 1 nodal points.
///
/// Example: q = 1 (n = 2)
///
/// Lagrange p(1);
/// p.set(0, 0.0);
/// p.set(1, 1.0);
///
/// It is the callers reponsibility that the points are distinct.
///
/// This creates a Lagrange polynomial (actually two Lagrange polynomials):
///
/// p(0,x) = 1 - x (one at x = 0, zero at x = 1)
/// p(1,x) = x (zero at x = 0, one at x = 1)
///
class Lagrange : public Variable
{
public:
/// Constructor
Lagrange(unsigned int q);
/// Copy constructor
Lagrange(const Lagrange& p);
/// Specify point
void set(unsigned int i, double x);
/// Return number of points
unsigned int size() const;
/// Return degree
unsigned int degree() const;
/// Return point
double point(unsigned int i) const;
/// Return value of polynomial i at given point x
double operator() (unsigned int i, double x);
/// Return value of polynomial i at given point x
double eval(unsigned int i, double x);
/// Return derivate of polynomial i at given point x
double ddx(unsigned int i, double x);
/// Return derivative q (a constant) of polynomial
double dqdx(unsigned int i);
/// Return informal string representation (pretty-print)
std::string str(bool verbose) const;
private:
void init();
const unsigned int q;
// Counts the number of time set has been called to determine when
// init should be called
uint counter;
std::vector<double> points;
std::vector<double> constants;
Event instability_detected;
};
}
#endif
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