Very nice rpn calc. Please add more color schemes - or better yet, add the ability to create your own color schemes. Also, it would be nice if you could make it so that the user can create custom layouts with the buttons of their choice and the ability to move the buttons or keys around on the layout.

This is not just a scientific calculator, it's a scientific calculator with an optional RPN mode. For those of us wedded to our HP, this is HUGE. One very nice feature is the suite of included constants and conversions. Not having to look these up will be a real time saver. The layout is fine, and turning the phone on its side brings up additional functions like logs, trig functions, etc. Definitely a good value, especially at the low price.

A great program which brings bittersweet emotions. Do I get rid of my beloved HP? I also agree that different skins would be nice. Maybe one that mimics popular HPs? Also, putting the RPN option in the settings so its permanent would be nice. But those are such small issues. The program is brilliant. Great job James. ...now if I could just figure out how to delete the iPhone calc ;)

If you use arithmetic notation you really don't need this; the new Apple scientific calculator will do just fine and there are not enough improvements here to justify the expense and allocation of memory. However, if you're like me and need (want, demand, etc.) an RPN calculator then this app is highly recommended. I still like my old HP11c but this will do the trick nicely.

PCalc is a rich, full-featured calculator, with support for RPN. If you're not familiar with RPN (Reverse Polish Notation), it's a more efficient method of entering a complex series of operations. PCalc has built-in unit conversions, engineering and scientific notation, and even handles hexadecimal, octal, and binary calculations. PCalc is already superb, and each update adds even more functionality and user options. PCalc is also available as a standard OS X application (which comes with a Dashboard Widget). I have both versions -- iPhone and OS X -- and consider them indispensable.

I purchased this app when it just came out and I'm really happy with it. However, I had to purchase other calculators for the conversions from feets to inches. I know there is a nice conversion with this cal but it would be really nice if you can convert inches to feet-inch; ie, 18" to 1'-6" or vice versa, also able to calculate +, -, X and / with these inch units; i.e. 1'-6" x 2 = 3'-0" and 1'-6" / 3 = 6".

I'm a big fan of PCalc and have used the application and the widget for years. When the opportunity to send James Thomson more money appeared in the form of PCalc for the iPhone, I jumped at the opportunity. So far it's the best iPhone application I've purchased.

This is my favorite application on the Ipod. I will continue to support this developer.

I go crazy when I don't have RPN so PCalc is the way to go. I've used it as my calculator on my Mac for years and now I have it on my iPhone! :-)

I have been using pcalc on OS X for years. It was the first app I purchased for my phone.

By far the best RPN calc Iphone app and worth the extra cost. Elegant appearance. Could use more memory registers.

This little calculator utility is fantastic! I am very impressed. I will use it mainly for accounting and other basic financial purposes. When you have a long calculation, the tape function is very helpful to see if you entered your numbers in correctly. A job well done - high recommended!

I've always liked PCalc on the Mac, and having it on the phone is great. It's very well executed, easy to use, and has fun little touches like "Shake to Clear" and the use of "42". (A note about "Shake to Clear": it didn't quite work the way I expected until I rapped the phone on my desk. Which worked. Once. ;-))

I have used the Mac version of PCalc for years. I've checked virtually all of the similar apps on both Mac and Windows, and none have had the breadth of function, correctness, ease of use or polish of PCalc. This version of PCalc brings all of that goodness to your pocket. The new calculator in iPhone 2.0 isn't bad, but PCalc is better and a must for RPN-heads.

After a year with my iPhone, I finally have a great scientific calculator! This is a must-have application for any scientist or engineer, and the developer's support is outstanding.

This calculator has a lot of functions. At first it may look like the built-in iPhone 2.0 calculator, but it does a lot more! In addition to trig and log functions, it has all kinds of unit conversions, physical constants, base conversion and arithmetic, and also RPN mode -- for all the HP users. It is very easy to use, and gives you a choice of how you want the digits to appear. I've put PCalc on the first page of icons on my iPhone to replace the built-in one. PCalc has been a favorite of Mac users for years, and it's great to have it on the iPhone now. This is the one to get!

Yes, the 2.0 upgrade gives you a scientific calculator. But this gives you much more. RPN, conversions, stack views and "paper tapes," the ability to do long calculations with the parenthesis tool, access to more constants than you'll probably need. Could it be more pretty? Yes. Would graphing be nice? Sure. Does it work really, really well as a scientific calculator? YOU'D BETTER BELIEVE IT WORKS. Dinging it because it lacks a certain esthetic or doesn't have features it doesn't offer is lame. It's a frakking calculator, and a great one at that. It is easy to use. If you can type on the keyboard for Mail or Notes than you won't have a problem. And it takes a feature from the keyboard by showing you the key you are hitting, something the built in science calculator doesn't do. It does what it does very well, very efficiently, and very quickly. Having purchased calculators for other handheld devices I think this is a steal. 5 very enthusiastic stars.

I bought it, I love it and I use the Mac version as well. The only unfortunate thing is it is ugly.

While it's true you get a scientific calculator included with iPhone OS 2.0, it does not support RPN (or parentheses), either of which make doing complicated calculations much easier. PCalc also has unit conversions, constants, and binary/hex/octal modes which are great for programmers. If you want to get a feel for the app before you buy, try out the Mac OS X version of PCalc.

This Calc program blows away the iPhone 2.0 scientific calculator.... It does everything I need and more. I really appreciate being able to go between different bases (such as base 10, binary, hex). Highly recommend.

I have admit I find those reviews knocking this product to be very misleading. I've been an engineer for 35 years and have used multiple HP RPN hardware calculators and and several products like this on the Palm platform. For those of use who actually use a product such as this to make a living, I think this is a solid, well designed tool that I would pay $10 for without a second thought! Graphing on the iphone? Can you say toy? Skins? Who cares! This is a tool I can use easily and one that will allow me to leave one more heavy device on my desk and out of my travel bag. My only confusion was that the TRIG functions are accessible via the "2nd" key in the landscape mode. Once you can get there this thing maximizes screen space for my fat fingers and leaves the skins for those who really don't need this! Climbing from soapbox... Thanks to the author. I've been waiting for just this product.

I like the programmers features (I've never been one to do hex/oct/dec conversions in my head), but the layout in scientific/programmer mode is strange. the number buttons are on the left side, which makes entering values awkward. I'd suggest at the very least an option to place the mirror the current layout, placing the digits on the right and function keys on the left.

I suffer from a heavy HP RPN addiction and PCalc fills the bill for me. The keys enlarge when you approach them like the standard iPhone keyboard giving it, with sound feedback, the right "feel"

I have been using HP calculators for over three decades. This RPN calculator provides some basic scientific capability, base conversions and some binary operations, and an excellent set of unit conversions and constants. I like the inclusion of 2^x and log base 2, which you don't usually see.

While iPhone 2.0 has a scientific calculator built in, you'll find it cannot do calculations in hexadecimal, or the less common octal or binary. Switch to Hex mode, and the statistical buttons change to logic operations --- functionality that you won't notice just from looking at the screen shot on the store. The calculator can also be switched into RPN mode, which many people still prefer from the days of their HP calculators. PCalc has many features that go well beyond what Apple provides, and if you happen to need those features it's well worth the $10. I wouldn't mind seeing some color coding of keys to make (for instance) the numbers stand out a bit more, but by and large this is a great app at a fair price.

PCalc transforms your iPhone or iPod touch into the coolest scientific calculator ever. In vertical orientation it looks like an attractive standard calculator, albeit one with conversions (the A->B button), constants (the 42, representing the Ultimate Answer to Life, The Universe, and Everything), and more. But hold your device horizontally and it becomes a powerful scientific calculator, complete with RPN mode, hex, octal, and binary modes, and a simulated paper tape for tracking calculations as you go.