1 package liblinear;
2
3 class L2R_L2_SvcFunction implements Function {
4
5 private final Problem prob;
6 private final double[] C;
7 private final int[] I;
8 private final double[] z;
9
10 private int sizeI;
11
12 public L2R_L2_SvcFunction( Problem prob, double Cp, double Cn ) {
13 int i;
14 int l = prob.l;
15 int[] y = prob.y;
16
17 this.prob = prob;
18
19 z = new double[l];
20 C = new double[l];
21 I = new int[l];
22
23 for (i = 0; i < l; i++) {
24 if (y[i] == 1)
25 C[i] = Cp;
26 else
27 C[i] = Cn;
28 }
29 }
30
31 public double fun(double[] w) {
32 int i;
33 double f = 0;
34 int[] y = prob.y;
35 int l = prob.l;
36 int w_size = get_nr_variable();
37
38 Xv(w, z);
39 for (i = 0; i < l; i++) {
40 z[i] = y[i] * z[i];
41 double d = 1 - z[i];
42 if (d > 0) f += C[i] * d * d;
43 }
44 f = 2 * f;
45 for (i = 0; i < w_size; i++)
46 f += w[i] * w[i];
47 f /= 2.0;
48
49 return (f);
50 }
51
52 public int get_nr_variable() {
53 return prob.n;
54 }
55
56 public void grad(double[] w, double[] g) {
57 int i;
58 int[] y = prob.y;
59 int l = prob.l;
60 int w_size = get_nr_variable();
61
62 sizeI = 0;
63 for (i = 0; i < l; i++) {
64 if (z[i] < 1) {
65 z[sizeI] = C[i] * y[i] * (z[i] - 1);
66 I[sizeI] = i;
67 sizeI++;
68 }
69 }
70 subXTv(z, g);
71
72 for (i = 0; i < w_size; i++)
73 g[i] = w[i] + 2 * g[i];
74 }
75
76 public void Hv(double[] s, double[] Hs) {
77 int i;
78 int l = prob.l;
79 int w_size = get_nr_variable();
80 double[] wa = new double[l];
81
82 subXv(s, wa);
83 for (i = 0; i < sizeI; i++)
84 wa[i] = C[I[i]] * wa[i];
85
86 subXTv(wa, Hs);
87 for (i = 0; i < w_size; i++)
88 Hs[i] = s[i] + 2 * Hs[i];
89 }
90
91 private void subXTv(double[] v, double[] XTv) {
92 int i;
93 int w_size = get_nr_variable();
94
95 for (i = 0; i < w_size; i++)
96 XTv[i] = 0;
97
98 for (i = 0; i < sizeI; i++) {
99 for (FeatureNode s : prob.x[I[i]]) {
100 XTv[s.index - 1] += v[i] * s.value;
101 }
102 }
103 }
104
105 private void subXv(double[] v, double[] Xv) {
106
107 for (int i = 0; i < sizeI; i++) {
108 Xv[i] = 0;
109 for (FeatureNode s : prob.x[I[i]]) {
110 Xv[i] += v[s.index - 1] * s.value;
111 }
112 }
113 }
114
115 private void Xv(double[] v, double[] Xv) {
116
117 for (int i = 0; i < prob.l; i++) {
118 Xv[i] = 0;
119 for (FeatureNode s : prob.x[i]) {
120 Xv[i] += v[s.index - 1] * s.value;
121 }
122 }
123 }
124
125 }