code: public Coordinate enuToEcef( Coordinate cEnu ) {
          double[][] enu = new double[][]{{cEnu.x}, {cEnu.y}, {cEnu.z}};
          RealMatrix enuMatrix = MatrixUtils.createRealMatrix(enu);
  
          RealMatrix deltasMatrix = _inverseRotationMatrix.multiply(enuMatrix);
  
          double[] column = deltasMatrix.getColumn(0);
          double cecfX = column[0] + _ecefROriginX;
          double cecfY = column[1] + _ecefROriginY;
          double cecfZ = column[2] + _ecefROriginZ;
  
          return new Coordinate(cecfX, cecfY, cecfZ);
      }
docs: Converts an ENU coordinate to Earth-Centered Earth-Fixed (ECEF).
  
  @param cEnu the enu coordinate.
  @return the ecef coordinate.