code: private double adjustBetaSign( double beta , List<Point3D_F64> nullPts ) {
  		if( beta == 0 )
  			return 0;
  
  		int N = alphas.numRows;
  
  		int positiveCount = 0;
  
  		for( int i = 0; i < N; i++ ) {
  			double z = 0;
  			for( int j = 0; j < numControl; j++ ) {
  				Point3D_F64 c = nullPts.get(j);
  				z += alphas.get(i,j)*c.z;
  			}
  
  			if( z > 0 )
  				positiveCount++;
  		}
  
  		if( positiveCount < N/2 )
  			beta *= -1;
  
  		return beta;
  	}
docs: Use the positive depth constraint to determine the sign of beta