Implementation of pow(3m) function

[Marcus Leech]

I recently received a complaint from a user about the CPU-hungriness
  of the pow(3m) function in the UNIX C library.
I'm wondering about the efficiency of "standard" implementations of this
  (and other) math library functions for C.  Does pow(3m) conventionally
  use a logarithm table, or is it (ugh!) iterative, or some B.O.T?
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Marcus Leech, 4Y11             Bell-Northern Research  |opinions expressed
mleech at bnr.ca                  P.O. Box 3511, Stn. C   |are my own, and not
VE3MDL at VE3JF.ON.CAN.NA         Ottawa, ON, CANADA      |necessarily BNRs