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 the iPhone and iPad versions 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.
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