Halcyon Calc vs RPN
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Halcyon Calc
A powerful calculator app for students, engineers, and scientists. It handles complex numbers, symbolic expressions, unit conversions, and matrix operations, with advanced plotting and programming capabilities.
- Complex number calculations
- Symbolic expression manipulation
- Unit conversion with custom units
- Matrix and vector operations
- Symbolic plotting
- Programming of custom operations
- Statistical data analysis
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For students, engineers, scientists or people who fondly remember classic calculators, Halcyon Calc is a great application for manipulating numbers and even symbolic expressions. Features: - Use this calculator on an iPhone, iPod Touch or an iPad - Use your finger to quickly scroll through the stack to review intermediate results - Copy and paste support - Over 225 built-in operations, including trig, logarithms, real functions, complex operations and more - Allows you to work with real, complex and integer numbers. - Real and complex numbers can be displayed in standard, fixed, scientific and engineering format - Use over 120 built-in units to perform unit conversion or create your own units if the one you want is not already there - Integer numbers can be displayed in decimal, hexadecimal, octal and binary bases - Work with real and complex matrices and vectors. - Enter symbolic expressions and solve them for different values. Even better, solve quadratic formulas, collect and expand factors and terms, find minima, maxima and roots of any expression. - Plot symbolic expressions in X/Y coordinates. Pan the coordinate space by dragging the plot in any direction. Zoom in and out using a pinch gesture. - Determine symbolic derivative, taylor series or numeric integral of an expression. - Store numbers, lists, strings and expressions in symbols. Create hierarchies of symbols to allow you to organize your calculations. - Create sequences of calculator commands into programs, creating your own operations which you can then include in expressions. - Store statistical data and calculate totals, averages, standard deviations, linear regressions, etc over that data. - Calculate the probabilities associated with standard distributions like the normal, F and T distributions.
RPN
This app simulates a legendary 1970s programmable calculator, offering advanced features for scientists and engineers. It allows users to run programs, manage virtual cards, and access hundreds of free program cards from its website.
- Virtual program and data cards
- Virtual paper tape printer
- Database-driven card manager
- Create, label, and organize unlimited cards
- Effortless saving of card collections
- Formatted program listings
- Live display of stack and registers
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A dream calculator of the 70's, priced at $3,200 in today's dollars, now affordable for everyone! RPN-97 Pro is the first complete simulation of Hewlett-Packard's legendary HP-97 programmable calculator for iOS. Produced from 1976 to 1984, the HP-97's features coupled with its capability to store programs on magnetic cards made it a huge success among scientists, engineers and other professionals. Thousands of programs were written for it. Now you can run them right on your iPad, with more ease and faster than ever before. To get you started quickly, download hundreds of program cards from our website for free. What users said: “The most delightful app I possess. The magnet card reader emulation rocks. Would have paid much more for this." "As the owner of an actual working HP 97 calculator, I am blown away with this new simulator. Simply fabulous." "Whoever coded this my hat goes off to you - what a professional piece of work, incredible app." RPN-97 Pro is fully compatible with RPN-67 Pro, its companion simulator of the HP-67 calculator. Features: • Virtual program and data cards • Virtual paper tape printer • Powerful database-driven card manager • Create, label, and organize a virtually unlimited number of cards • Use iTunes to effortlessly save entire card collections on your Mac/PC • Sharing: e-mail, AirDrop, Dropbox, copy, paste, print • Formatted listing clearly showing labels and targets of branches • E-mail listings and let the recipient paste the text right into RPN-97 • Print listings on any AirPrint-compatible printer • Program listing on paper tape shows subroutine nesting • Edit paper tape • E-mail paper tape, or print it via AirPrint • Cut/copy/paste displayed value or program steps • Paste HP-67 or HP-97 listings from other sources into RPN-97 and run them • "Live" display of stack, memory registers, program counter, flags • Show program usage notes • 30 selectable background images, even add your own • Much faster than a real HP-97 • Low-battery indicator (iPad charge 10% or less) • Compatible with RPN-67 Pro and RPN-67 SD, CuVee Software's HP-67 simulators • Supports hardware keyboard While RPN-97 Pro can work exactly like a real HP-97, changing a simple setting will turn the app into a super-charged HP-97: • Up to 999 program steps, 8 subroutine levels, 6 additional flags (F4...F9) • 100 additional registers • 100 additional labels • 100 built-in constants and conversions • More than 150 additional powerful operations and functions Plus: • 15 commands to print and manipulate any range of extended registers • Unrestricted register arithmetic • Exchange x with any register • Complex numbers mode, hyperbolic functions • Non-volatile memory - stack, registers, program, flags, paper tape • Status indicators for prefix keys (EXT, f, LBL, GTO, etc.) • Display showing thousands separators (optional) • Text output on paper tape in 10 colors, even simple plotting • Stack-of-stack: push/pop the entire stack on internal stack (4 levels) • Single-step into subroutines (optional) • Powerful debugging aids, including 10 breakpoints with counters • Keycodes translated to command name while entering or single-stepping a program • Change the duration of the PAUSE command • Cancel SST or BST operation by simply sliding your finger off the depressed key • Compress constants in programs into a single step (reversible) • Use existing programs in text format by a simple paste operation RPN-97 Pro comes with more than 130 programs pre-installed, including HP Standard Pac, HP Business Decisions Pac, HP Math Pac I, HP Stat Pac I, and HP Surveying Pac I. The simulator has been verified to correctly run the examples given in HP Civil Engineering Pac I, HP Clinical Lab Pac, HP E.E. Pac I, HP Games Pac I, HP M.E. Pac I, HP Navigation Pac I, as well as large number of programs published in Users' Library Solutions. For more information and free program downloads visit the RPN-97/67 website: cuveesoft.ch/rpn67
Screenshots
Verdict
The clearest difference is iOS requirement: RPN at 12.0 against Halcyon Calc's 16.6. On price, rating, review sentiment and ratings volume there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Halcyon Calc costs $4.99 and RPN $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.
On the App Store both sit at effectively the same score — 4.9 for Halcyon Calc against 4.9 for RPN. Both are backed by a comparable volume of ratings — 18 and 11 respectively. Written reviews split almost evenly too, at 100% and 100% positive.
Halcyon Calc ships an update every 4 months, RPN every 3 months. The most recent releases landed on September 22, 2026 and June 1, 2026 respectively.
| Parameter | Halcyon Calc | RPN |
|---|---|---|
| Price | $4.99 | $4.99 |
| Rating | 4.9 (18 ratings) | 4.9 (11 ratings) — better |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| Number of ratings | 18 — better | 11 |
| Update frequency | Every 4 months | Every 3 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPhone, iPad — better | iPad |
| Requires iOS | 16.6 | 12.0 — better |
| Further details — not scored | ||
| Size | 10 MB | 75 MB |
| Age rating | 4+ | 4+ |
| Developer | Halcyon Touch Software | Willy Kunz |
Customer experience
Halcyon Calc
RPN
In-app purchases
Halcyon Calc
No in-app purchases
RPN
No in-app purchases








