C Floating point arithmetic

[VLD/VMB]

You argue that because your data is only accurate to 2 or 3
significant figures, 6 to 7 place accuracy in the computation
is sufficient.  This is often simply not true; a numerical
analyst should make the determination.  I have seen enough
computations that produced total garbage to make me believe
that the naive user should get double precision by default.

I am in favor of supporting low-precision floating point in
C, as permitted by X3J11, but let's not make it the default.