:term:`NO_DFILE <NO_DFILE (DETCI)>`
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      Do use the last vector space in the BVEC file to write scratch DVEC rather than using a separate DVEC file? (Only possible if :term:`NUM_ROOTS <NUM_ROOTS (DETCI)>` = 1.) 

      * **Type**: :ref:`boolean <op_c_boolean>`
      * **Default**: false