SpicyRPN

SpicyRPN is a comprehensive multiprecision scientific and financial calculator for iPhone, iPad, and Mac, with both RPN and algebraic (ALG) entry modes.

Precision and versatility, in one calculator

Built for engineering, science, and business, the new SpicyRPN pairs a familiar instrument-style keyboard with a powerful modern numerical engine.

• 600-digit working precision by default. Choose from 16 to 10,000 decimal digits, with separate controls for displayed digits.
• RPN and ALG, side by side. Switch between independent stack and algebraic workspaces without losing unfinished work.
• Real and complex arithmetic. Work in rectangular or polar form, with complex scientific functions and easy component editing.
• A stack that grows with your work. Start with five registers; choose a fixed depth from 2 to 1,000 or an unlimited stack, and inspect every level.
• Scientific, statistical, and financial tools. From Gamma and error functions to regression, cash flows, bonds, and depreciation.
• 15 unit-conversion families. Convert everyday and engineering quantities, including temperature and torque.
• Your work stays with you. Calculations, unfinished entries, and settings are saved locally after each action.

Native on iPhone and iPad with iOS 18 or later, and Apple silicon Macs with macOS 15 or later.

Functions available on SpicyRPN

Entry, precision, and everyday tools

Orange f and blue g shifts put a broad set of functions within reach.

• RPN: ENTER, swap, roll, drop, stack inspection, Last X, and Last Y.
• ALG: parentheses, FUNC, ANS, equals, and explicit CPT worksheet calculations.
• Precision: PREC sets working precision; FIX sets displayed digits; choose fixed, scientific, or engineering notation.
• Number tools: exponent entry, backspace, sign change, reciprocal, absolute value, integer and fractional parts, rounding, modulo, and remainder.
• Constants and percentages: π, e, ln 2, random numbers, percent, percent change, and percent of total.
• Memory: ten numbered registers, arithmetic storage, and associative storage and recall.
• 15 conversion families: length, area, volume, mass, temperature, speed, acceleration, force, pressure, energy, power, time, frequency, angle, and torque.

An interface that adapts

Swipe between scientific and financial panels in portrait; see both together in landscape. Scroll long results with the exponent kept in view. Hardware keyboard support, VoiceOver, and separate offline HELP guides for RPN and ALG support the way you work.

Scientific, complex, and statistical calculation

• Powers and logarithms: squares, roots, general powers and roots, exponential functions, natural and common logs, base-2 and arbitrary-base logs.
• Trigonometry: sine, cosine, tangent, inverses, atan2, hyperbolic and inverse hyperbolic functions; degrees, radians, or grads.
• Special functions: Gamma, log-Gamma, factorial, log-factorial, erf, erfc, permutations, and combinations.
• Complex numbers: rectangular and polar forms, component editing and swapping, magnitudes, and complex elementary functions.
• Statistics: add or remove paired observations; means, weighted means, sample standard deviations, linear regression, estimated values, and correlation.

Use dedicated statistical keys in RPN or named statistical worksheets in ALG. Shared accumulators keep the same data available to both modes.

Precision you can control

The engine uses GMP, MPFR, and MPC. Working and display precision are independent: changing visible digits does not change calculation precision. Stored values retain the precision at which they were created.

Financial tools for the whole calculation

• Time value of money: solve for periods, interest rate, present value, payment, or future value, with BEGIN and END payment timing.
• Loans and interest: amortization, simple interest, and annual/monthly rate and period conversions.
• Cash flows: enter repeated, equally spaced flows, inspect them, and calculate NPV or IRR. Bounded IRR lets you choose the search interval.
• Bonds: price and yield for semiannual coupon bonds.
• Dates: Gregorian date arithmetic, days between dates, MDY or DMY, and actual-day or 30/360 day counts.
• Depreciation: straight-line, sum-of-years-digits, declining balance, and declining balance with a switch to straight-line.

RPN offers familiar store-and-solve keys. ALG uses explicit CPT calculations and named worksheets. Financial and cash-flow banks are shared between modes.

Interest rates are percentages per payment period. IRR searches find a bracketed root; some cash-flow patterns have multiple solutions. The manual explains the conventions and worked examples.