Calculator

Builds the true final price as a waterfall: stacked discounts, correct sales-tax base and cascade, tipping on the etiquette base with rounding, per-person split, and mid-market vs DCC conversion.

Format Conversion

Convert configuration files between dotenv .env, TOML, INI, Java .properties, YAML, JSON, HCL (Terraform/Vagrant native syntax) and Nix attribute sets, and emit Kubernetes ConfigMap or Secret manifests. Template placeholders (${VAR}, {{var}}, envsubst) are preserved verbatim, type inference provenance (string/int/float/bool/list) is tracked, HCL block labels fold into nested keys, and a round-trip diff calls out non-equivalent settings — dropped keys, re-typed values and rewrites — instead of coercing them silently.

Development

Convert Unix timestamps between hexadecimal and decimal/ISO — paste 0x5F6B3A2F, a bare 8-digit hex value, decimal seconds or milliseconds, or a date, and get every form back.

Text Processing

Run the UAX #9 Unicode bidirectional algorithm rule by rule — X1–X8 embedding levels, isolating run sequences, BD16 paired brackets with N0, W/N/I resolution and L1/L2/L4 reordering — and inspect every intermediate state.

Science & Education

1/f = 1/u + 1/v solved for f, u, or v: magnification, real/virtual image nature, and power in diopters.

Science & Education

Δt = γ·Δτ with γ = 1/√(1−v²/c²): both clock views for any speed below c, from the 0.6c hand-check case to muon lifetimes at 0.998c.

Science & Education

Rectangular-barrier WKB T ≈ e^(−2κa) vs exact transmission, reflection R = 1−T, and over-barrier partial reflection for electron, proton, or custom mass.

Science & Education

Δx·Δp ≥ ℏ/2: minimum Δp from Δx, minimum Δx from Δp, or a pair check with satisfaction ratio. Units m–pm and kg·m/s / g·cm/s / eV/c; optional mass derives Δv.

Math & Numbers

Balanced transportation problems as min-cost flow: successive shortest paths, MODI duals, reduced-cost optimality certificate, and full shipping plan.

Finance

Bootstrap the discount-factor and spot curve from treasury quotes, fit Nelson-Siegel or Svensson parametrically, and chart spot plus instantaneous forward curves with basis-point residuals.

Math & Numbers

Complete truth table (≤ 6 variables, 64 rows) with alphabetical variable order, per-row function values, and canonical Σm/ΠM forms.

Data Analysis

Class-stratified train/validation/test split or stratified k-fold for CSV/JSON datasets — seeded, reproducible, with distribution reports, leakage checks, SMOTE preview and CSV export.