Revert rev 1.8, which causes small (e.g. 2 ulp) errors for some inputs.  The trouble with replacing two floats with a double is that the latter has 6 extra bits of precision, which actually hurts accuracy in many cases.  All of the constants are optimal when float arithmetic is used, and would need to be recomputed to do this right.
Revert rev 1.8, which causes small (e.g. 2 ulp) errors for some
inputs.  The trouble with replacing two floats with a double is that
the latter has 6 extra bits of precision, which actually hurts
accuracy in many cases.  All of the constants are optimal when float
arithmetic is used, and would need to be recomputed to do this right.

Noticed by:	bde (ucbtest)

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase