# NumberF

> NumberF (Hex package `number_f`) is an Elixir library for number formatting, currency
> formatting, number-to-words conversion, financial and tax calculations, statistics,
> validation, and unit conversion. Everything is exposed through a single flat `NumberF`
> module. One runtime dependency (`decimal`), no configuration, Elixir 1.14+.

Install: add `{:number_f, "~> 0.3.0"}` to `deps` in `mix.exs`, then `mix deps.get`.

Key facts:
- Default currency unit is ZMW (Zambian Kwacha); pass a unit explicitly to override.
- 22 supported locales: en-US, en-GB, en-ZM, fr-FR, de-DE, es-ES, it-IT, nl-NL, pl-PL,
  sv-SE, pt-BR, ru-RU, tr-TR, ar-SA, hi-IN, ja-JP, ko-KR, zh-CN, th-TH, vi-VN, id-ID, ms-MY.
- Number-to-words spelling languages: en, fr, es, de. `NumberF.spelling_languages/0`
  lists them; an unsupported language raises rather than silently returning English.
- `ceiling/2` and `floor/2` take decimal places; `round_to/3` takes an increment.
- `variance/1` and `standard_deviation/1` are the POPULATION forms (divide by N).
  Use `sample_variance/1` / `sample_standard_deviation/1` for the sample forms (N-1).
- `combinations/2` returns an exact integer, not a float. So does `fibonacci/1`.
- Documentation is grouped: Formatting, Currency, Text, Financial, Tax, Statistics,
  Precision, Validation, Math, Units, Dates, Humanize, Internationalization, Introspection.
- Invalid input raises ArgumentError naming the bad argument. Formatters accept nil.
- The library makes no network calls; exchange rates and tax rates are supplied by the caller.

## Docs

- [Full documentation (llms-full.txt)](https://hexdocs.pm/number_f/llms-full.txt): Complete API reference as a single plain-text file.
- [HexDocs index](https://hexdocs.pm/number_f/llms.txt): Machine-readable index of every documentation page.
- [Cheatsheet](https://hexdocs.pm/number_f/cheatsheet.html): Every function with a verified example, on one page.
- [Getting Started](https://hexdocs.pm/number_f/getting-started.html): Installation and first steps.
- [FAQ](https://hexdocs.pm/number_f/faq.html): Common questions, including how NumberF compares to ex_cldr and ex_money.
- [Currency Formatting](https://hexdocs.pm/number_f/currency-formatting.html): Currency symbols, placement, and precision.
- [Financial Calculations](https://hexdocs.pm/number_f/financial-calculations.html): Interest, EMI, and amortization.
- [Internationalization](https://hexdocs.pm/number_f/internationalization.html): Locale-aware formatting and spelling.

## New in 0.3.0

- Statistics: `percentile/2`, `quartiles/1`, `iqr/1`, `correlation/2`, `covariance/2`,
  `linear_regression/2`, `z_score/3`, `z_scores/1`, `weighted_mean/2`, `geometric_mean/1`,
  `harmonic_mean/1`, `summary/1`, `moving_average/2`, `cumulative_sum/1`, `normalize/1`,
  `outliers/2`, `remove_outliers/2`, `frequency_distribution/1`, `trimmed_mean/2`,
  `coefficient_of_variation/1`
- Financial: `present_value/3`, `future_value/3`, `npv/2`, `irr/2`, `amortization_schedule/3`,
  `roi/2`, `cagr/3`, `effective_annual_rate/2`, `loan_payment/3`, `annuity_payment/3`,
  `annuity_present_value/3`, `annuity_future_value/3`, `depreciation_straight_line/3`,
  `depreciation_declining_balance/4`, `break_even_point/3`, `payback_period/2`
- Validation: `valid_iban?/1`, `valid_isbn?/1`, `valid_ean?/1`, `valid_upc?/1`, `card_brand/1`,
  `luhn_check_digit/1`, `valid_luhn?/1`, `valid_routing_number?/1`, `valid_imei?/1`,
  `valid_currency_code?/1`, `valid_percentage?/1`
- Precision: `clamp/3`, `safe_divide/3`, `sign/1`, `round_half_away_from_zero/2`,
  `round_half_even/2`
- Math: `permutations/2`, `fibonacci/1`, `fibonacci_sequence/1`, `prime_factors/1`,
  `divisors/1`, `digits/1`, `digit_sum/1`, `digital_root/1`, `reverse_number/1`,
  `palindrome?/1`, `perfect_square?/1`, `nth_root/2`, `log_base/2`, `to_base/2`,
  `from_base/2`, `to_hex/1`, `from_hex/1`, `to_binary/1`, `from_binary/1`, `to_octal/1`,
  `from_octal/1`
- Formatting: `accounting_format/2`, `format_bytes/2`, `format_duration/2`,
  `significant_figures/2`, `format_significant/2`, `with_sign/2`, `pad_number/3`,
  `pluralize/3`
- Dates: `quarter/1`, `quarter_start/1`, `quarter_end/1`, `fiscal_year/2`, `days_in_month/2`,
  `leap_year?/1`, `week_number/1`, `month_start/1`, `month_end/1`, `age_in_months/2`

## Common tasks

- Format currency: `NumberF.currency(1234.567, "USD")` -> `"USD 1,234.57"`
- Locale currency: `NumberF.format_currency(1234.56, "fr-FR")` -> `"1 234,56 €"`
- Locale number: `NumberF.format_number(1234567.89, "de-DE")` -> `"1.234.567,89"`
- Thousands separator: `NumberF.comma_separated(1234567.89)` -> `"1,234,567.89"`
- Abbreviate: `NumberF.abbreviate_number(1_234_567)` -> `"1.2M"`
- Number to words: `NumberF.to_words(42.75, "Dollars", "Cents")` -> `"Forty Two Dollars And Seventy Five Cents"`
- Spell decimals: `NumberF.spell_number(1.05, "en")` -> `"One point zero five"` (digit by digit)
- Spell in another language: `NumberF.spell_number(42, "fr")` -> `"Quarante-deux"`
- Ordinal: `NumberF.ordinal(21)` -> `"21st"`
- Roman numerals: `NumberF.to_roman(1999)` -> `"MCMXCIX"`; `NumberF.from_roman("MCMXCIX")` -> `1999`
- Simple interest: `NumberF.simple_interest(1000, 0.05, 2)` -> `100.0`
- Compound interest: `NumberF.compound_interest(1000, 0.05, 2, 12)` -> `104.94`
- Loan EMI: `NumberF.calculate_emi(100_000, 0.10, 12)` -> `8791.59`
- VAT: `NumberF.calculate_vat(100, 0.2)` -> `%{net: 100.0, vat: 20.0, gross: 120.0}`
- VAT-inclusive: `NumberF.calculate_vat(120, 0.2, true)` -> `%{net: 100.0, vat: 20.0, gross: 120.0}`
- Income tax: `NumberF.Tax.calculate_income_tax(75_000, brackets)` -> `%{tax: 12248.5, effective_rate: 0.1633}`
- Statistics: `NumberF.mean/1`, `median/1`, `mode/1`, `variance/1`, `standard_deviation/1`, `range/1`
- Sample statistics: `NumberF.sample_variance/1` -> `4.571428571428571`, `sample_standard_deviation/1`
- Bankers rounding: `NumberF.bankers_round(2.5, 0)` -> `2.0`
- Float comparison: `NumberF.approximately_equal(0.1 + 0.2, 0.3)` -> `true`
- Credit card check (Luhn): `NumberF.is_valid_credit_card?("4111111111111111")` -> `true`
- Byte sizes: `NumberF.memory_size_cal(1_048_576)` -> `"1.0 MB"` (handles up to PB)
- Abbreviate: `NumberF.abbreviate_number(1_500_000_000_000)` -> `"1.5T"`; negatives supported
- Phone: `NumberF.format_phone("14155552671", "US")` -> `"+1 (415) 555-2671"`
- Temperature: `NumberF.celsius_to_fahrenheit(25)` -> `77.0`
- Decimal sum: `NumberF.sum_decimal([Decimal.new("1.10"), Decimal.new("2.20")])` -> `Decimal.new("3.30")`
- Clamp: `NumberF.clamp(15, 0, 10)` -> `10`
- Safe divide: `NumberF.safe_divide(10, 0)` -> `0.0`
- Percentile: `NumberF.percentile([1,2,3,4,5,6,7,8,9,10], 25)` -> `3.25`
- Loan schedule: `NumberF.amortization_schedule(100_000, 0.10, 12)` -> list of `%{period:, payment:, principal:, interest:, balance:}`
- NPV / IRR: `NumberF.npv(0.1, [-1000, 300, 400, 500, 600])` -> `388.77`; `NumberF.irr(flows)` -> `{:ok, 0.2489}`
- IBAN: `NumberF.valid_iban?("GB82 WEST 1234 5698 7654 32")` -> `true`
- Card network: `NumberF.card_brand("4111111111111111")` -> `:visa`
- Byte size: `NumberF.format_bytes(1_500_000)` -> `"1.5 MB"`; `base: :binary` for MiB
- Duration: `NumberF.format_duration(3725)` -> `"1h 2m 5s"`; `format: :clock` -> `"01:02:05"`
- Accounting: `NumberF.accounting_format(-1234.56, unit: "$")` -> `"($1,234.56)"`
- Base conversion: `NumberF.to_base(255, 16)` -> `"FF"`; `NumberF.from_base("FF", 16)` -> `255`
- Quarter / fiscal year: `NumberF.quarter(~D[2024-08-22])` -> `3`; `NumberF.fiscal_year(~D[2024-08-22], 4)` -> `2025`

## Modules

- `NumberF` — flat facade over everything below.
- `NumberF.Currency`, `NumberF.Currencies`, `NumberF.Formatter`, `NumberF.CustomFormatter` — formatting.
- `NumberF.Financial`, `NumberF.Calculations`, `NumberF.Statistics`, `NumberF.Precision`, `NumberF.Tax` — calculation.
- `NumberF.I18n` — locale-aware formatting, parsing, and spelling.
- `NumberF.Metrics` — metric/imperial and temperature conversion.
- `NumberF.NumbersToWords`, `NumberF.NumberToWord` — textual representation.
- `NumberF.Validation`, `NumberF.Memory`, `NumberF.Randomizer`, `NumberF.Helper` — validation and utilities.
- `NumberF.DateCalculations` — age, business days, payment terms.
- `NumberF.Registry` — runtime module and function discovery.

## Optional

- [GitHub repository](https://github.com/jamesnjovu/elixir_number_functions): Source, issues, and contribution guide.
- [Hex package](https://hex.pm/packages/number_f): Release history and download stats.
- [Changelog](https://github.com/jamesnjovu/elixir_number_functions/blob/master/CHANGELOG.md): Version history.