Peak intensity follows a checked signed amplitude, so cancellation and growth are separate rows. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Same-sign terms add before intensity
Two same-sign training terms give amplitude 2 and intensity 4. The square happens after the signed sum is known.
F=1+1=2,I=F2=4
Signed amplitude controls the peak intensity
The scan compares addition, cancellation, and a larger same-sign sum. Intensity follows the squared amplitude in every row.
terms+,++,−+,+,+F203I409
More same-sign terms make a larger squared peak
The three-term row gives amplitude 3 and intensity 9. It is still a sign-only training model, not a full crystallographic form factor.