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1 package JSci.maths.wavelet.haar;
2
3 import JSci.maths.wavelet.FWT;
4
5 public class FastHaar extends FWT {
6
7 public FastHaar() {
8 }
9
10 static final float[] scale = {(float)(1.0/Math.sqrt(2)),(float)(1.0/Math.sqrt(2))};
11 static final float[] wavelet = {-scale[1],scale[0]};
12
13 private static void transform (float[] v,int last) {
14 float[] ans=new float[last];
15 int half=last/2;
16 try {
17 for(int k=0;;k++) {
18 ans[k+half]=v[(2*k+0)]*wavelet[0]+v[(2*k+1)]*wavelet[1];
19 ans[k]=v[(2*k+0)]*scale[0]+v[(2*k+1)]*scale[1];
20 }
21 } catch (IndexOutOfBoundsException  e) {}
22 System.arraycopy(ans,0,v,0,last);
23 }
24
25
28 public void transform (float[] v) {
29 int last;
30 for (last=v.length;last>2;last/=2) {
31 transform(v,last);
32 }
33 if(last!=2)
34 System.err.println("Careful! this should be a power of 2 : "+v.length);
35 }
36
37 public void invTransform(float[] v) {
38 int last;
39 for (last=2;2*last<=v.length;last*=2) {
40 invTransform(v,last);
41 }
42 if(last!=v.length)
43 System.err.println("Careful! this should be a power of 2 : "+v.length);
44
45 }
46
47
50 private static void invTransform (float[] v, int last) {
51 int ResultingLength=2*last;
52 float[] ans=new float[ResultingLength];
53 try {
54 for(int k=0;;k++) {
55 ans[(2*k+1)]+=scale[1]*v[k]+wavelet[1]*v[k+last] ;
56 ans[(2*k+0)]+=scale[0]*v[k]+wavelet[0]*v[k+last] ;
57 }
58 } catch (IndexOutOfBoundsException e) {}
59 System.arraycopy(ans,0,v,0,ans.length);
60 }
61
62 }
63 |
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