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
|
/**************************************************************************
* *
* Regina - A Normal Surface Theory Calculator *
* Computational Engine *
* *
* Copyright (c) 1999-2008, Ben Burton *
* For further details contact Ben Burton (bab@debian.org). *
* *
* 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; 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. *
* *
* You should have received a copy of the GNU General Public *
* License along with this program; if not, write to the Free *
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, *
* MA 02110-1301, USA. *
* *
**************************************************************************/
/* end stub */
#include "maths/nray.h"
namespace regina {
void NRay::scaleDown() {
NLargeInteger gcd; // Initialised to 0.
unsigned i;
for (i = 0; i < vectorSize; i++) {
if (elements[i].isInfinite() || elements[i] == zero)
continue;
gcd = gcd.gcd(elements[i]);
if (gcd < 0)
gcd.negate();
if (gcd == one)
return;
}
if (gcd == zero)
return;
for (i = 0; i < vectorSize; i++)
if ((! elements[i].isInfinite()) && elements[i] != zero)
elements[i].divByExact(gcd);
}
NRay* intersect(const NRay& first, const NRay& second,
const NVector<NLargeInteger>& hyperplane) {
// Return (hyperplane * first) second - (hyperplane * second) first.
// Negate this if (hyperplane * first) is negative.
NLargeInteger firstCoeff(hyperplane * first);
NRay* ans = dynamic_cast<NRay*>(second.clone());
(*ans) *= firstCoeff;
(*ans).subtractCopies(first, hyperplane * second);
(*ans).scaleDown();
if (firstCoeff < NLargeInteger::zero)
(*ans).negate();
return ans;
}
} // namespace regina
|
