code: public static DMatrixRMaj stripReal(ZMatrixD1 input , DMatrixRMaj output ) {
          if( output == null ) {
              output = new DMatrixRMaj(input.numRows,input.numCols);
          } else if( input.numCols != output.numCols || input.numRows != output.numRows ) {
              throw new IllegalArgumentException("The matrices are not all the same dimension.");
          }
  
          final int length = input.getDataLength();
  
          for( int i = 0; i < length; i += 2 ) {
              output.data[i/2] = input.data[i];
          }
          return output;
      }
docs: Places the real component of the input matrix into the output matrix.
  
  @param input Complex matrix. Not modified.
  @param output real matrix. Modified.