Math & Numbers
Plot a normal-distribution bell curve as SVG with z-score markers, interval or tail-probability shading, and 68/95/99.7 standard-deviation bands.
normal-distribution-plotterFinance
Side-by-side monthly rent-vs-buy simulation: mortgage amortization, property tax, insurance, HOA and maintenance against rent plus renter insurance; the renter invests the down payment and monthly savings at an opportunity-cost rate. Outputs break-even year on net sale proceeds, per-year differential NPV, SALT-cap-aware after-tax cash flows, a differential IRR, and a ±20% tornado sensitivity chart.
rent-vs-buy-total-cost-of-ownership-mortgage-tax-insurance-maintenance-irr-tutorDate & Time
Parse ISO 8601 durations, validate ISO 8601-2 extensions, run calendar-true arithmetic, sort by real length at an anchor, and diff datetimes.
iso-8601-duration-parser-arithmetic-workbenchMath & Numbers
Enumerate primes up to 10⁷ (or within [m, n]) with the classic sieve; shows base primes, crossing-out operations, exact counts, and up to 200 primes.
sieve-of-eratosthenesMath & Numbers
Textbook Hungarian algorithm for 2–8 × 2–8 assignment problems: row/column reductions, augmenting-path zero matching, König line covers, and substitution-verified optimal assignments.
assignment-problem-solverMath & Numbers
Activity-on-node CPM: ES/EF/LS/LF, total float, project duration, and every critical path; cycles and unknown predecessors are rejected.
critical-path-methodMath & Numbers
Two-person zero-sum games: saddle-point test first, then mixed strategies from a single-phase simplex LP with dual shadow prices, verified by security-level checks.
game-theory-zero-sumMath & Numbers
Dijkstra with a full per-iteration trace: settled nodes, relaxations, distance table, and the final path; undirected or directed, negative weights rejected, unreachable targets reported.
graph-shortest-pathMath & Numbers
Minimal SOP via Quine–McCluskey with essential prime implicants, exact minimum cover, Gray-coded Karnaugh map, and full-assignment verification.
boolean-algebra-simplifierMath & Numbers
Numeric convergence tests for Σ aₙ: nth-term, ratio, root, p-series comparison, and integral test; alternating series classified by Leibniz with a sum estimate.
series-convergence-testerMath & Numbers
Union, intersection, difference, symmetric difference, and Cartesian product of two comma-separated sets, with cardinalities and capped pair display.
set-operations-calculatorMath & Numbers
Table lookup of the unilateral Z-transform for 11 standard pairs, with parameter substitution, region of convergence, derivation note, and optional numeric X(z₀) evaluation.
z-transform-calculator