RPN Comp Calc

A serious RPN calculator with a four-level stack, built the way HP taught us: ENTER, then operate. No equals key, no parentheses, no ceremony. Full scientific keyboard: trig and inverse trig (2nd key), hyperbolic functions and their inverses, logs and exponentials in every base you actually use, powers and roots, factorial and gamma, plus a curated screen of twelve physical constants (CODATA/SI-2019) one tap away. Then the part most calculators skip: a true complex-number mode. Flip to CPX and every register holds a complex value. Enter real and imaginary parts directly, see results in rectangular or polar form (r ∠ θ), and use exp, log, powers, trig and hyperbolics across the complex domain with principal-value conventions. Degrees or radians, honored everywhere. Designed for people who think in stacks: classic stack lift, roll, swap and drop; a live four-register display so you always see T, Z, Y and X; degree/radian and fixed/scientific display toggles; haptic keys. No ads. No accounts. No tracking. No network access at all. Your calculator is yours.