Richard Clark wrote:

Hi John,

Yes, this confirms the shift to double precision in EZNEC lowering
artifacts in the fine data.

However, I think it goes beyond simple matters of single or dual
precision math. When I was designing Fourier Analysis packages while
I was on contract to HP, I discovered there was a world of variability
in math library's transcendental functions.

Microsoft's product was abysmal, whereas Borland's was superlative. A
telling example is that for the transform of a sine wave into the
frequency domain under Microsoft math libraries, the noise floor was
at 60 to 80 dB below the fundamental peak with harmonics. When I
switched to Borland math libraries, there was a single bin response
and the noise floor plunged to 200dB down!

snip
73's
Richard Clark, KB7QHC

Richard

I am not surprised with your result after having used various MS
compilers over the years. Do you have any idea what the real
differences were in the libraries? Borland C always seemed better, more
robust at error handling, and more accurate.

I noticed similar problems back in the late 80's with MS C, but never
really needed the precision, and work pressure being what it was....

tom
K0TAR