Chart methodology
Charting is not a “metaphysical black box” — it is deterministic computation over traditional calendrical rules. Every step of this engine — what it computes with, whether rules were altered, where the schools disagree — is laid out in the open.
1. The engine: professional-grade, deterministic, checkable
The charting core is a professional-grade Zi Wei Dou Shu engine: the star-placement logic is implemented rule by rule against mainstream classics such as the Zi Wei Dou Shu Quanji and Quanshu, so any researcher who knows the rules can verify every step. Version pinning means the same birth data yields the same chart today, next year, always.
Our engine implementation already includes fixes for all known edge cases:
- · Leap-month Santai/Bazuo placement fix
- · Boundary fix for lunar 1958-12-30 Chen hour
- · Ming Palace anomaly fix for Heaven/Earth/Human charts
- · Zhongzhou late-Zi Human chart fix
2. Zero modification of star-placement rules
We make no “secondary creation” on the placement algorithm: star positions, brightness tables and Si Hua lookup tables are all untouched. Every difference comes only from explicitly declared configuration — each disputed convention is a visible switch on the chart, not a silent choice made for you.
| Convention | Default | Optional |
|---|---|---|
| Charting school | Standard | Zhongzhou (affects Ming Zhu, Jiekong, Suipo and other minor stars) |
| Si Hua table | Flying Star / Quanji edition | San He / Quanshu edition (3 stems differ: Geng, Ren, Wu) |
| Annual boundary | First day of the first lunar month | Lichun (Start of Spring) |
| Decade boundary | First day of the first lunar month | Lichun (Start of Spring) |
| Nominal age counting | Age increments at Spring Festival | Age increments at birthday |
| Late Zi hour attribution | To the next day | To the same day |
3. Fixed correction order, labeled on the chart
Before charting, the birth time is corrected in a fixed order: birth-place time zone → true solar time (longitude ±4 min/degree + equation of time) → early/late Zi convention. Every correction is labeled on the chart and can be reviewed at any time — you will never get a different hour from the one you entered without knowing why.
The calendar covers 1900–2100 — two hundred years with full lunar leap-month support.
4. We don't hide the disputes
The Zi Wei schools do disagree on a few rules (leap month, late Zi hour, Si Hua table). Our approach: implement them all, label the current convention, and switch with one click. See Leap month rules, Early/late Zi hour, Si Hua schools.