caltib 0.3.2

Tibetan calendar toolkit (traditional + reform engines).

caltib

High-Precision Tibetan Calendrical Math

caltib is a rigorous Python library designed to unify 15th-century historical algorithms with 21st-century astrophysics. It provides a polymorphic framework for evaluating traditional lunisolar calendars alongside modern mathematical reforms.

Live Demonstration

The library can be evaluated directly in the browser without local installation. The web calendar runs completely client-side via WebAssembly: 👉 Launch the caltib Web App

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Key Features

• Unified API: Evaluate traditional engines (Phugpa, Mongol, Tsurphu, etc.) and modern reforms (L0–L6) using a single, harmonized interface.
• Progressive Reforms: A tiered sequence of engines advancing from pure-integer mean motion (L0) and fixed-iteration Picard solvers (L1–L3) to strictly reproducible floating-point models (L4–L5) and JPL-powered numerical integration (L6).
• Strict Reproducibility: L0–L5 engines utilize integer sine-tables or Chebyshev minimax polynomials to ensure bit-for-bit consistency across all CPU architectures.
• Localized Physics: Support for geographical location injection to accurately handle spherical sunrise boundaries and civil day-numbering conventions.
• Design & Diagnostics Laboratory: A professional-grade toolkit for designing new calendar parameters via continued fractions and analyzing secular drift over millennia.

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Installation

caltib is designed to be lightweight. The core package has zero external dependencies, making it highly suitable for embedded environments or web deployment.

Core: Traditional engines & Reform Tiers L0-L5

pip install caltib

Tools: Diagnostic charting & parameter design (requires NumPy & Matplotlib)

pip install "caltib[tools]"

Ephemeris: JPL DE422 integration & L6 engine (requires Skyfield & jplephem)

pip install "caltib[ephemeris]"

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Quickstart

Basic Day Query

from datetime import date
import caltib

# Standard traditional lookup
info = caltib.day_info(date(2026, 2, 21), engine="mongol")
print(f"Mongol Tithi: {info.tibetan.tithi}")

Advanced Localized Reform

from caltib.engines.specs import LOC_MONTREAL
import caltib

# Build an L3 engine localized to Montreal coordinates.
# L3 utilizes fixed-iteration rational Picard solvers and spherical sunrise geometry.
engine = caltib.get_calendar("l3", location=LOC_MONTREAL)
info = engine.day_info(date(2026, 2, 21))

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Diagnostics & Design

The library includes a comprehensive diagnostic suite to rigorously analyze calendar accuracy and historical deviations.

• Secular Drift: Track how sidereal calendars decouple from the tropical equinox over 1,500-year timescales.
• Variance Mapping: Visualize the error propagation and variance of traditional anomaly approximations.
• Rational Design: Derive optimal convergents for constructing new calendar architectures.

Example Usage:

# Analyze secular acceleration against JPL DE422 numerical integration
caltib diag analysis --engine mongol --ephem de422

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License: Distributed under the MIT License. Created by Tsogtgerel Gantumur.