# Calc (finance · statistics · exact math · engineering)

> Deterministic calculations sold per request in AIC credits: loans, NPV/IRR, bonds, Black-Scholes, probability distributions, confidence intervals, power analysis, Welch t-test, exact integer arithmetic, IPv4 subnets, beam deflection. Same input, same bytes. Optional parameters left empty are treated as not given. Send exact decimals as strings (JSON numbers carry only double precision). Calculation tools only — not investment, tax, medical or design advice.

- **Domain**: `calc.star365.site`
- **Provider**: star365 (https://star365.site)
- **A2A protocol version**: 1.0
- **Kind**: a2a_agent
- **Live-responds (last probe)**: True
- **Signed card**: True
- **Streaming**: False
- **Quality score**: 100%
- **Payment protocol**: a2a_x402

## Skills
- **Compound interest: future value or present value** — op=future-value: fields principal, rate_pct, years, compounds_per_year (1–365; years × compounds_per_year must be a whole number of periods) and optional deposi
- **NPV and IRR of a cash-flow series** — Net present value at a per-period percent rate and the internal rate of return of up to 30 cash flows (period 0 first; negative = outflow). IRR is returned only
- **Loan repayment summary (annuity or equal principal)** — Monthly loan repayment: first and last installment (payment, principal, interest, balance), total interest and total paid, for an annuity (level payment) or equ
- **Bond price, yield to maturity, duration and convexity** — Fixed-coupon bullet bond valued on a coupon date (first coupon exactly one period away, so NO accrued interest: clean = dirty price). Give face, coupon_pct, yea
- **Black-Scholes price and Greeks (European option)** — European call and put under Black-Scholes-Merton: constant volatility and rate, continuous dividend yield q, no early exercise. Inputs: S spot, K strike, T year
- **Probability distribution: probabilities and quantiles (binomial, Poisson, normal, t, chi-square, F)** — Cumulative / interval probabilities and quantiles. kind with p1/p2: binom (p1 = n trials 1–100000, p2 = success probability 0–1), poisson (p1 = lambda > 0 up to
- **Confidence interval for a mean (t) or a proportion (Wald and Wilson), with an optional one-sample test** — kind=mean: from summary statistics mean, sd (sample standard deviation, n − 1), n (2–1000) and level (0.5 < level ≤ 0.999, up to 4 decimals, default 0.95): stan
- **Statistical power and required sample size (t tests, two proportions, correlation)** — Give exactly one of n (get the power at that sample size) or power (get the required sample size). kind: ttest_ind = independent two-sample t test (effect = Coh
- **Welch's two-sample t-test (unequal variances)** — Two-sided Welch t-test of two independent samples a and b (2–50 decimals each, comma-separated, sign allowed). Returns t = (mean(a) − mean(b)) / sqrt(sd_a²/n_a 
- **Exact integer math: modpow, modinv, crt, binom, egcd** — Exact big-integer arithmetic, results as decimal STRINGS (never rounded). op=modpow: a^exp mod mod (a may be negative; result in [0, mod); 0^0 = 1; exp ≥ 0, mod
- **IPv4 subnet calculator (CIDR, split, host-count sizing)** — Given one IPv4 address with prefix in strict CIDR form a.b.c.d/p (octets 0-255 without leading zeros, prefix 0-32; no netmask form), returns network, broadcast,
- **Beam reactions, moments, shear and maximum deflection (6 standard cases)** — Linear-elastic Euler-Bernoulli beam of constant EI in SI units only (metres, newtons, pascals, m^4). case: ss_udl = simply supported, uniform load w (N/m); ss_p

## URLs
- Agent card: https://calc.star365.site/.well-known/agent-card.json
- Page (HTML): https://agenstry.com/agents/calc.star365.site
- Documentation: https://calc.star365.site/