> ## Documentation Index
> Fetch the complete documentation index at: https://docs.jyotiguide.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Classical References Behind Jyoti Guide's Calculations

> The four primary classical and modern sources behind every Jyoti Guide calculation, with a feature-to-source mapping table for tracing any number.

Jyoti Guide does not invent its methods. Every derived quantity — from a planet's Shadbala score to a festival's tithi — follows a recognised authority in Vedic astronomical or astrological literature. This page identifies the four principal sources, explains what each one grounds in the app, and ends with a mapping table so you can trace any computed value back to the text that defines it.

<Note>
  Where a method has more than one accepted form, the app exposes the choice — for example, the Shadbala **reading school** and the **ayanāṁśa** setting — rather than silently picking one. This means you can always align the output with the text or lineage you follow.
</Note>

## B. V. Raman — *Graha and Bhava Balas*

This focused manual on the numerical strength of planets and houses is the app's primary source for the **[Shadbala](/guides/shadbala)** system. Specifically, it grounds:

* The **six balas** and their components: Sthāna-bala, Dig-bala, Kāla-bala, Cheṣṭā-bala, Naisargika-bala, and Dṛk-bala.
* The **Bhāva-bala** calculation (house strength), and the **Ishta/Kashta Phalas** (benefic and malefic results).
* The **minimum virūpa thresholds** the app uses to produce a planet's strength ratio — Sun 300, Moon 360, Mars 300, Mercury 420, Jupiter 390, Venus 330, Saturn 300.

The component maxima and the Naisargika-bala values listed in [Shadbala computation](/reference/shadbala-computation) follow this text directly.

## P. V. R. Narasimha Rao — *Vedic Astrology: An Integrated Approach*

A comprehensive modern textbook with worked examples covering fundamentals through advanced techniques, this is the source that grounds the **broadest range of the app's features**:

* **Fundamentals** — rāśis, grahas, bhāvas, karakas, aspects, and yogas, introduced in the [Concepts](/concepts/the-sidereal-sky) section.
* **[Divisional charts](/concepts/divisional-charts)** — the full Shoḍaśavarga and the interpretive principles for each varga (Part 1).
* **[Ashtakavarga](/guides/ashtakavarga)** — BAV and SAV construction, reductions, and transit scoring (ch. 12).
* **[Vimśottarī daśā](/guides/vimshottari-dasha)** and other daśā systems, with period-sequencing rules (Part 2).
* **[Gochara / transits](/guides/gochara-transits)** — transit analysis from the Lagna and Moon, combined with Ashtakavarga bindus and nakṣatra triggers (Part 3).
* **[Tājaka / Varshaphal](/guides/tajaka-varshaphal)** — annual charts, Tājaka yogas, and annual daśā systems (Part 4).
* **Muhūrta** and the **impact of birth-time error** — behind [Choosing a date](/examples/choose-a-date) and the [birth-time guidance](/help/troubleshooting#birth-time-uncertainty) in Troubleshooting (Part 5, ch. 32).

## V. P. Jain — *Elements of Astronomy* (for astrologers)

A lean, technically precise treatment of the astronomy underlying the astrology. It grounds the app's astronomical engine rather than its interpretive layer:

* **Sidereal vs. tropical time** — the mathematical basis for converting between the two frameworks.
* The **ayanāṁśa** and the **precession of the equinoxes** — how and why the sidereal and tropical zodiacs drift apart over centuries. See [Ayanāṁśa options](/reference/ayanamsa).
* **Lunar months and tithis** — the arithmetic of the luni-solar calendar, behind the Panchāng's tithi calculations.
* **Sunrise, sunset, and ascendant calculation** — the spherical trigonometry used to place the Lagna. See [The sidereal sky](/concepts/the-sidereal-sky) and [Panchāng](/guides/panchang).

## Bṛhat Parāśara Horā Śāstra (BPHS)

The foundational classical compendium attributed to the sage Parāśara, and the ultimate textual authority behind the app's core framework:

* **Parāśarī aspects** — the full-strength and special aspects of each graha used throughout the chart.
* **Whole-sign houses** — the house system the app uses by default.
* **Divisional chart definitions** — the canonical method for deriving each of the sixteen vargas.
* **Vimśottarī daśā** — the period lengths and sequence that the app implements.

The app's **"Classical BPHS" reading school** and several of its Shadbala calculation options refer directly to the values given in this text.

***

## Feature-to-source mapping

| Feature                                      | Principal source(s)                   |
| -------------------------------------------- | ------------------------------------- |
| Sidereal positions, ayanāṁśa, sunrise/sunset | Jain; BPHS                            |
| Signs, planets, houses, aspects              | Rao; BPHS                             |
| Divisional charts (Shoḍaśavarga)             | Rao; BPHS                             |
| Shadbala (six balas, thresholds, Bhāva-bala) | **Raman**; BPHS                       |
| Ashtakavarga (BAV / SAV)                     | Rao; BPHS                             |
| Vimśottarī daśā                              | Rao; BPHS; Jain                       |
| Gochara (transits)                           | Rao                                   |
| Tājaka / Varshaphal                          | Rao                                   |
| Ashtakūṭa compatibility                      | Classical matchmaking literature; Rao |
| Panchāng (five limbs, muhūrta)               | Jain; Rao                             |