docs: public static void convertNcc( TupleDesc_F64 input , NccFeature output ) {
  
  		if( input.size() != output.size() )
  			throw new IllegalArgumentException("Feature lengths do not match.");
  
  		double mean = 0;
  		for (int i = 0; i < input.value.length; i++) {
  			mean += input.value[i];
  		}
  		mean /= input.value.length;
  
  		double variance = 0;
  		for( int i = 0; i < input.value.length; i++ ) {
  			double d = output.value[i] = input.value[i] - mean;
  			variance += d*d;
  		}
  		variance /= output.size();
  
  		output.mean = mean;
  		output.sigma = Math.sqrt(variance);
  	}