The basic Calculator app that comes with iOS is good for simple calculations, and if you rotate your phone into landscape orientation, it even provides some rudimentary scientific-calculator functions. But if it’s a full-featured scientific calculator you seek—or if you’d just like a great calculator for your iPad, which inexplicably doesn’t include one—you’ll want to look elsewhere.
My personal favorite remains TLA Systems’s $10 PCalc (App Store link). It’s overflowing with features, including scientific operations, conversions, constants, and even user-defined functions. And you get it all in an interface that can look as simple or complete, and as modern or retro, as you prefer.
(If you don’t need all of the features of the full version of PCalc—or if you’re not sure, so you don’t want to spend $10—you can instead pick up the free PCalc Lite, which offers all the basics of the full version, but lets you add some or all of the latter’s features a la carte. The nice thing about this approach is that upgrading PCalc Lite with all of the available add-on packs—Conversion, Theme, Programmer, Engineer, Power User, and Multiple Line—costs the same $10 as buying the full version, so there’s no risk in starting small.)
As with the previous versions, you get all the standard scientific-calculator fare: inverse; roots; exponents; trigonometric functions; nested operations; decimal, hexadecimal, octal, and binary modes; RPN (Reverse Polish Notation—both HP and non-HP versions); and much more. There’s still a time-stamped virtual tape for revisiting (and sharing) your calculations, as well as a register (called the stack in RPN mode) that displays memory contents and decimal-, hex-, octal-, and binary-base versions of the current number.
To make it easy to perform common calculations, PCalc provides preset conversions in a slew of categories: angles (for converting between six units of angular measurement), area (12 units), bytes (13), cooking (15), currency (33), density (6), energy (14), force (8), fuel efficiency (8), length (14), lighting (12), power (10), pressure (11), speed (11), temperature (5), time (9), torque (4), volume (17), and weight (10). For example, to convert meters to feet, you enter the number of meters, tap the Conversions button (labeled A>B), tap Length, and then tap Meters. You see a list of your measurement converted to every available unit of measure; tap Feet and the result is entered in the main display.
You can sort each list of conversion options alphabetically or by size, and the most-recently used conversions in each category are conveniently listed at the top of the list. If you don’t find a particular conversion listed, you can add your own. For many people, PCalc’s conversions feature alone will be worth the price of admission.
The app also includes a generous assortment of predefined functions, which are more-complex calculations. These are sorted across six categories: Complex Numbers (for example, finding the square root of [X+iY]), Financial, Memory (functions that use numbers stored in memory), Special (for example, for finding permutations), Trigonometric (calculations beyond the standard trig-related buttons, such as the hyperbolic cotangent), and User. Again, you can add your own here—more on that below.
If you frequently use scientific and engineering constants, there are plenty of those, too. Tap the 42 button—because what more important constant is there?—and you get quick access to known parameters in seven basic categories: astronomical (for example, the radius of the earth and standard gravity), atomic (e.g., the Rydberg Constant), electromagnetic (e.g., elementary charge), mathematical (e.g., pi, e, and the golden ratio), physicochemical (e.g., Avogadro Constant), universal (e.g., the speed of light), and user (those you’ve added manually, though you can also add your own constant to any of the other categories). Choose any constant, and it’s entered in the main display.
Speaking of the display, PCalc’s “LCD” is highly configurable: You can choose the number of lines (with separate settings for horizontal and vertical orientations), and choose what each line is used for (for example, for particular registers or stack levels)—you can even two-finger swipe up or down to view fewer or more lines, respectively, on the fly. You can also change the background color and the font and color of the digits. You can copy results from the display for pasting elsewhere, and you can paste numbers copied elsewhere to use them in your calculations. And PCalc supports undo and redo via dedicated buttons, screen swipes, or (for undo) a gentle shake of the device.
You can customize PCalc’s overall appearance via thirteen different interface themes and a number of key layouts: three vertical layouts and three horizontal layouts on the iPad, and eight vertical layouts and ten horizontal layouts on the iPhone. (The iPad’s larger screen accommodates more keys, so there’s less need for different key layouts—the iPhone layouts each contain a different subset of keys.) The app can even automatically switch to a darker theme at night, and there’s a nice Basic key layout that hides most of the extras for everyday use. (On the iPad, I use Basic for my vertical layout, and the default scientific layout for horizontal orientation.)
Some of the new themes are decidedly iOS 7-influenced, but the developer has also kept the older themes around if you prefer the retro look. (I still have a soft spot for Twilight and High Power, which remind me of my old HP RPN calculators.) And if you prefer using a hardware keyboard with your iOS device, PCalc fully supports external keyboards, and even supports a nice array of shortcuts for functions. (You can find a keyboard-shortcut cheat sheet in the app’s Help screens.)
Besides the different layout options, the main differences between PCalc on the iPhone and the iPad are that the latter of course has room for more keys and a larger display, and that the iPad version uses popovers for accessing settings, constants, and conversions, while the iPhone version switches to different screens. As I mentioned in my review of version 2.0, PCalc’s interface on the iPhone is very good, but—as with every scientific calculator I’ve tested—it’s even better on the iPad thanks to the extra screen space.
New and improved
Since my review of version 2, TLA Systems has made a bunch of tweaks and improvements to PCalc, some of them in updates to version 2 and others in PCalc 3, the current major version. In addition to additional themes and key layouts (included in the totals above), the latest PCalc includes 64-bit support for Apple’s latest iOS devices; VoiceOver support for all actions, results, and touch typing; more options for customizing the interface, including bigger (and bolder) button text and support for iOS 7’s Dynamic Type feature; and more-consistent button locations when switching between landscape and portrait orientation.
But there have been major feature additions, as well. One of the biggest is that, as mentioned above, you can create custom functions and conversions, so if a particular feature you need is missing from PCalc, there’s a good chance you can add it yourself with a little work. When creating a new function, you can choose from over 40 different commands that handle everything from basic mathematical operations to trigonometric functions to conditionals; you can also designate which register/stack is used for each part of your function. All your custom functions and conversions are automatically synced across your iOS devices via iCloud; you can also email a set of functions to another PCalc user. (Dr. Drang has an excellent tutorial on creating user-defined functions and conversions. He also has a few examples of user-created function files you can import, including a bunch of financial, probability, and weather-related calculations.)
For fans of iOS automation, PCalc 3 also provides its own URL schemes for inter-app actions. Added in version 2.5 and updated in 3.0, you can use these schemes with applications such as Launch Center Pro, Drafts, and Editorial to open and configure PCalc from within those apps, and even perform calculations using data from those apps.
The little things
Some of my favorite PCalc features are the little touches. For example, the app automatically scales text size as more numbers appear on the display, so when you’re doing simple one-line calculations, you see bigger numbers. There’s a dedicated frac key for entering fractions—tapping 3 frac 7 enters 3/7. (You can also double-tap the . key to perform the same action.) You can disable auto-lock, so your iPhone or iPad stays awake while you’re using PCalc, and an Accounting mode automatically adds a decimal point and rounds numbers to two decimal places. When in algebraic (non-RPN) mode, you can repeat the last calculation by simply pressing the = button again.
A nifty feature added in version 2.7 is a “ticker tape” history banner just below the main display—the type is small, but a quick swipe lets you browse your recent calculations. You can also enable key popovers that function much like the ones you see on iOS’s standard keyboard—when you tap a key, a larger version of it appears until you release it. (This feature is especially handy for increasing accuracy on the iPhone’s smaller keys.) I also like the option to display a blinking editing cursor in the display, so you know whether a number is one you’re still entering or the result of a calculation.
Smartphones and tablets don’t give you the tactile feel of a hardware calculator, but they allow app developers to create the perfect calculator—whatever that might be for a particular individual. For example, you can choose a natural-language calculator such as Soulver, or even one like MyScript that lets you write your equations right on the screen. In the case of PCalc, TLA Systems has designed the ultimate scientific calculator: one that’s fantastic today, but that’s also regularly updated with new features, functions, and faces.
When I reviewed PCalc 2, I was impressed that the developer had squeezed so much into the program without making it unwieldy. PCalc has since gained even more features, and yet it’s just as easy to use as before—in some ways easier, thanks to interface improvements. Whether you’re performing serious scientific calculations, doing high-school physics homework, or just converting everyday measures, PCalc has the features and interface for you. And if you want to try before you buy, you can download the free Lite version and then pay for just the features you need, when you need them.
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Dan is former Macworld senior editor. You can find him on the web at danfrakes.com.