The NVH library contains operators which are used for frequency domain and acoustics
    functions.
    All operations in the NVH library operate with complex
      data and output complex data. This may seem counterintuitive, considering all the operations
      available (at this point) should be viewed as real data (the imaginary part will always be
      0.0), but because data types get added to an existing subcase, and the subcase is complex, the
      output of these operators should be viewed at 0˚ within HyperWorks.The acoustics operators are designed to maximize flexibility and are designed to work
        together, and can accommodate both vector and scalar participation input.