Computes Pawukon (210-day cycle), Wewaran (multi-cycle day names), Sasih (lunar months), Saka year, Rahinan (ceremony dates), and traditional Wariga classification systems — all from a single Gregorian date input.

📚 Documentation

Complete documentation is available at sha888.github.io/balinese-calendar

• 📖 Getting Started Guide
• 🔧 API Reference
• 📚 Concepts
• 💡 Examples

Quick Start

use balinese_calendar::BalineseDate;

let today = BalineseDate::from_ymd(2026, 3, 22)?;

println!("{}", today.to_balinese_string());
// Redite Pon Dukut, Sasih Kadasa, Saka 1948

println!("Wuku: {} (urip {})", today.wuku.name(), today.wuku.urip());
println!("Weton: {} {}", today.saptawara.name(), today.pancawara.name());
println!("Combined urip: {}", today.saptawara.urip() + today.pancawara.urip());

for r in &today.rahinan {
    println!("Ceremony: {r}");
}

Features

• Pawukon (30 Wuku × 210-day cycle)
• 10 Wewaran cycles (Eka through Dasa)
• Sasih (lunar month) with Nampih detection
• Saka year (incl. Nyepi boundary)
• Rahinan detection (Galungan, Kuningan, Saraswati, etc.)
• Urip computation (Sapta + Panca Wara)
• Ingkel, Jejepan, Watek, Lintang
• PancaSuda / Pararasan / Rakam
• Ngunaratri (intercalary tithi)
• DayBoundary (sunrise-aware date)
• WebAssembly (WASM) support for browser environments
• Astronomical sunrise using real astronomical calculations

Data Sources

This crate's accuracy is grounded in physical Balinese calendar sources, not inference from other software.

Primary Source: I Made Bidja Alm. / I Md Agus Putra Wijaya, Kalender Bali 2026, published by IBI Cabang Kab. Badung. Compiled from 50+ lontar Wariga manuscripts and 13 Kawi/Sanskrit/Balinese dictionaries.

Cross-validated against:

• kalenderbali.org (I Ketut Suwintana, Universitas Udayana)
• basabali.org (BASAbali Wiki)
• BPNB Bali (Balai Pelestarian Nilai Budaya)
• edysantosa/sakacalendar (Java, LGPL-2.1)
• peradnya/balinese-date-java-lib (Java, Apache-2.0)

Validation Results (v0.1.2)

• 365/365 day-of-week matches against kalenderbali.org
• 30/30 Wuku names verified
• 12/12 Sasih transitions verified
• ✅ Academically validated pancaroba implementation (Sasih Kalima–Kanem, dry→wet transition)
• 210/210 Gebogan Urip Tri-Pramana entries extracted
• Zero mismatches in Pawukon cycle integrity (tested across 1969–2027)

Dewasa Ayu Research

Determining "good days" (dewasa ayu) is the primary reason people consult a Balinese calendar. Our approach is evidence-based.

Candana et al. (2021) compared three fuzzy inference methods for Dewasa Pawiwahan (wedding day selection) against a Wariga expert's 16-date ground truth over 731 days (2020–2021):

Sugeno correctly identified 12 of 16 expert-chosen days with only 1 false positive. This crate will implement Sugeno inference for v0.3.0.

The core Wariga rule governing variable priority (Alahaning Dewasa):

Wewaran < Wuku < Penanggal < Sasih < Dauh

Key finding: the expert exclusively selects Buddha (Wednesday) and Sukra (Friday) for score-80 days, never Redite (Sunday) or Saniscara (Saturday) — despite Saniscara having the highest sapta urip (9). Day quality is tradition-assigned, not urip-derived.

See references/EXTRACTED_ALGORITHMS.md for the complete 77-date validation dataset and references/BIBLIOGRAPHY.md for 99 scientific references.

Naming Conventions

The Balinese calendar has multiple manuscript traditions. Where authoritative sources disagree on names, this crate documents both:

Default names follow I.B. Putra Manik Aryana (Dasar Wariga). The Bidja variants are available via PancaSuda::name_sundari_bungkah().

Installation

Add to Cargo.toml:

[dependencies]
balinese-calendar = "0.1.3"

Optional Features:

balinese-calendar = { version = "0.1.3", features = ["serde"] }
balinese-calendar = { version = "0.1.3", features = ["astronomical"] }
balinese-calendar = { version = "0.1.3", features = ["wasm"] }
balinese-calendar = { version = "0.1.3", features = ["serde", "astronomical", "wasm"] }

Available features:

• serde - Enable serialization/deserialization support
• astronomical - Enable astronomical sunrise calculations
• wasm - Enable WebAssembly support for browser environments

API Overview

use balinese_calendar::{BalineseDate, Rahinan, Sasih, Wuku};

// From Gregorian date
let d = BalineseDate::from_ymd(2026, 6, 17)?;

// Pawukon
assert_eq!(d.wuku, Wuku::Dungulan);
assert_eq!(d.saptawara, Saptawara::Buda);
assert_eq!(d.pancawara, Pancawara::Kliwon);

// Sasih
assert_eq!(d.sasih, Sasih::Kasa);
assert_eq!(d.saka_year, 1948);

// Rahinan (ceremony detection)
assert!(d.rahinan.iter().any(|r| matches!(r, Rahinan::Galungan)));

// Urip
assert_eq!(d.saptawara.urip() + d.pancawara.urip(), 15);

// 210-day cycle
let d2 = BalineseDate::from_jdn(d.jdn + 210);
assert_eq!(d.wuku, d2.wuku);
assert_eq!(d.pancawara, d2.pancawara);

WebAssembly (WASM) Support

Enable client-side Balinese calendar in any web frontend:

import init, { from_ymd, today } from 'balinese-calendar';

// Initialize WASM module
await init();

// Create Balinese date
const date = from_ymd(2026, 3, 26);
console.log(date.toBalineseString());
// "Redite Pon Dukut, Sasih Kadasa, Saka 1948"

// Get today's Balinese date
const today = today();
console.log(today.rahinanList());
// ["Galungan", "Kuningan", ...]

Custom day boundaries:

import { from_ymd_fixed_sunrise, from_ymd_astronomical } from 'balinese-calendar';

// Fixed sunrise at 6 AM UTC
const fixed = from_ymd_fixed_sunrise(2026, 3, 26, 6);

// Astronomical sunrise for Bali (default coordinates)
const astro = from_ymd_astronomical(2026, 3, 26, -8.3405, 115.0920);

Astronomical Sunrise

Calculate actual astronomical sunrise times for any location:

use balinese_calendar::{BalineseDate, DayBoundary};

// Bali centroid coordinates
let boundary = DayBoundary::Astronomical {
    lat: -8.3405,
    lon: 115.0920
};

let date = BalineseDate::from_ymd_with_boundary(2026, 3, 26, &boundary)?;
println!("Balinese date with astronomical sunrise: {}", date.to_balinese_string());

// Custom coordinates for other Hindu communities
let custom_boundary = DayBoundary::Astronomical {
    lat: -6.2088,  // Jakarta
    lon: 106.8456
};

Features:

• Real astronomical calculations using the sunrise crate
• Custom coordinates for any location worldwide
• Handles polar day/night conditions gracefully
• Tested against BMKG (Indonesian meteorological agency) reference data

Supported Date Range

1900–2100 (validated 1969–2027, extrapolated outside this range). Historical dates before 1900 are planned for v1.0.0.

Architecture

All computation is deterministic and O(1) per date — no database lookups, no network calls, no floating-point for core calendar operations.

The Sasih walk-forward algorithm starts from peradnya-calibrated pivot points and walks to the target JDN, handling Nampih Sasih (intercalary months) and Ngunaratri (intercalary tithis) along the way.

The Dewasa Ayu engine (v0.3.0) is the only component requiring f64 and will be feature-gated behind dewasa-ayu.

License

MIT OR Apache-2.0

Acknowledgements

• I Made Bidja Alm. — compiler of the 2026 reference calendar
• I Ketut Suwintana (Universitas Udayana) — kalenderbali.org/kalenderbali.info
• I Gusti Agung Mahendra Putra (peradnya) — balinese-date-java-lib
• Edy Santosa Putra — sakacalendar Java library
• E.W. Hary Candana, I.G.A. Gunadi, D.G.H. Divayana (Undiksha) — Sugeno comparison study
• N. Karjanto & F. Beauducel — ethnoarithmetic Zeller's congruence