Precision: this page vs the VOACAP you download
This port computes in 64-bit floating point and matches voacapl built with
-fdefault-real-8 bit for bit. The voacapl you download computes in
32-bit. On 1,000 random circuits (METHOD 30, all 24 hours), about 3 in 4 output
files differ somewhere, almost always by one unit in the last printed digit:
99.74% of SNR values print the same, and 99.98% are within 1 dB. In 21 of
219,072 cells the 32-bit build takes a different ray (take-off angle, hop count or
mode), which moves SNR by up to 39 dB. The other cells more than 1 dB apart are
far above the MUF, at SNRs below −250 dB. REL is never off by more than 0.10.
On 150 area maps (32,971 grid points), SNR and signal never differ by more than
1.1 dB, and REL by no more than 0.02.