public override int inverse(Block vb, Object vl, float[][] fin, int[] nonzero, int ch)
{
//System.err.println("Residue0.inverse");
int i=0;
for(i=0;i<ch;i++)if(nonzero[i]!=0)break;
if(i==ch)return(0); /* no nonzero vectors */
return(_2inverse(vb, vl, fin, ch));
}