Structure-Factor Intensity Ledgers

Systematic Absence Is Zero Amplitude

A missing peak is a checked zero source, not a weak nonzero peak. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Opposite signs can remove a peak

The zero-source amplitude is 0 and the intensity is 0.

F=1+(−1)=0I=0F=1+(-1)=0\quad I=0
X-ray systematic absenceA checked zero amplitude is the only accepted absence claim.termtermsigned sumF=0I=0F=0I=0accepted=1

Absence is not a weak ratio branch

The absence helper accepts bit 1 only when amplitude and intensity are exactly zero.

accepted=1F=0I=0\text{accepted}=1\quad F=0\quad I=0
X-ray systematic absenceA checked zero amplitude is the only accepted absence claim.termtermsigned sumF=0I=0F=0I=0accepted=1