blob: 40973cc081b84af1d2068b7aca628e9fc7208a8a (
plain)
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
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
|
/** \file smoke/intern/LU_HELPER.cpp
* \ingroup smoke
*/
#include "LU_HELPER.h"
int isNonsingular (sLU LU_) {
for (int j = 0; j < 3; j++) {
if (LU_.values[j][j] == 0)
return 0;
}
return 1;
}
sLU computeLU( float a[3][3])
{
sLU result;
int m=3;
int n=3;
//float LU_[3][3];
for (int i = 0; i < m; i++) {
result.piv[i] = i;
for (int j = 0; j < n; j++) result.values[i][j]=a[i][j];
}
result.pivsign = 1;
//Real *LUrowi = 0;;
//Array1D<Real> LUcolj(m);
//float *LUrowi = 0;
float LUcolj[3];
// Outer loop.
for (int j = 0; j < n; j++) {
// Make a copy of the j-th column to localize references.
for (int i = 0; i < m; i++) {
LUcolj[i] = result.values[i][j];
}
// Apply previous transformations.
for (int i = 0; i < m; i++) {
//float LUrowi[3];
//LUrowi = result.values[i];
// Most of the time is spent in the following dot product.
int kmax = min(i,j);
double s = 0.0;
for (int k = 0; k < kmax; k++) {
s += (double)(result.values[i][k]*LUcolj[k]);
}
result.values[i][j] = LUcolj[i] -= (float)s;
}
// Find pivot and exchange if necessary.
int p = j;
for (int i = j+1; i < m; i++) {
if (abs(LUcolj[i]) > abs(LUcolj[p])) {
p = i;
}
}
if (p != j) {
int k=0;
for (k = 0; k < n; k++) {
double t = result.values[p][k];
result.values[p][k] = result.values[j][k];
result.values[j][k] = t;
}
k = result.piv[p];
result.piv[p] = result.piv[j];
result.piv[j] = k;
result.pivsign = -result.pivsign;
}
// Compute multipliers.
if ((j < m) && (result.values[j][j] != 0.0f)) {
for (int i = j+1; i < m; i++) {
result.values[i][j] /= result.values[j][j];
}
}
}
return result;
}
void solveLU3x3(sLU& A, float x[3], float b[3])
{
//TNT::Array1D<float> jamaB = TNT::Array1D<float>(3, &b[0]);
//TNT::Array1D<float> jamaX = A.solve(jamaB);
// Solve A, B
{
if (!isNonsingular(A)) {
x[0]=0.0f;
x[1]=0.0f;
x[2]=0.0f;
return;
}
//Array1D<Real> Ax = permute_copy(b, piv);
float Ax[3];
// permute copy: b , A.piv
{
for (int i = 0; i < 3; i++)
Ax[i] = b[A.piv[i]];
}
// Solve L*Y = B(piv)
for (int k = 0; k < 3; k++) {
for (int i = k+1; i < 3; i++) {
Ax[i] -= Ax[k]*A.values[i][k];
}
}
// Solve U*X = Y;
for (int k = 2; k >= 0; k--) {
Ax[k] /= A.values[k][k];
for (int i = 0; i < k; i++)
Ax[i] -= Ax[k]*A.values[i][k];
}
x[0] = Ax[0];
x[1] = Ax[1];
x[2] = Ax[2];
return;
}
}
|
