to a first approximation

to a first approximation
 adj.

   1. [techspeak] When one is doing certain numerical computations, an
   approximate solution may be computed by any of several heuristic
   methods, then refined to a final value. By using the starting point of
   a first approximation of the answer, one can write an algorithm that
   converges more quickly to the correct result.

   2. In jargon, a preface to any comment that indicates that the comment
   is only approximately true. The remark "To a first approximation, I
   feel good" might indicate that deeper questioning would reveal that
   not all is perfect (e.g., a nagging cough still remains after an
   illness).
    

to a first approximation

   1. When one is doing certain numerical computations, an
   approximate solution may be computed by any of several
   heuristic methods, then refined to a final value.  By using
   the starting point of a first approximation of the answer, one
   can write an algorithm that converges more quickly to the
   correct result.

   2. In jargon, a preface to any comment that indicates that the
   comment is only approximately true.  The remark "To a first
   approximation, I feel good" might indicate that deeper
   questioning would reveal that not all is perfect (e.g. a
   nagging cough still remains after an illness).

   [{Jargon File}]