This is a valid idea - though there are already a ton of calculators on the iPhone store and so we'd be competing against a saturated marketplace. One reason we did this project was the fact that most online calculators have terrible user interfaces and don't support things like complex numbers, or a traditional stack.

Just because there's a ton, doesn't mean its saturated. Moreover, do the owners of those apps have the ability to direct 10k users daily towards downloading their app? I would seriously look into it. Same with Android. Its silly to dismiss the iphone just because there are competitors. You can kick their ass even though they were first.

Edit: I should also add, the iPhone/mobile apps would likely far outstrip the sales of the $15 download, because people are used to buying iPhone apps, and Apple has made it much easier than buying from you. I would even suggest reversing the flow, so to speak, and talk about how iPhone users can find a free version online from their home or work computers whenever they want.

Good point. We created this calculator using just JS and CSS so it should be really simple to port to the new Pre, which is our plan. However, our background is not in programming so starting up iPhone programming might be a bit of a trip...

Have you considered who/how you're marketing this to? Maybe you could find a way to target engineering and science students. What does the $15 version offer that the online one doesn't? That wasn't immediately obvious to me, but I didn't look to long.

How does the calculator handle something like solving a matrix of complex numbers. I had to do that a lot in linear circuit analysis and would have loved a better tool to do it with.

The desktop version runs standalone in a borderless window and includes six color schemes and the ability to close the side bar. My background is in EE, so we designed the linear equation solver to handle complex number (both in polar and rec format) which is perfect for solving circuit problems. So you can enter in your mesh loops and solve for various complex values. We'll have some documentation on how to do this, but basically if you have a set of simultaneous equations with complex coeff you can enter them in each box and solve for the answers..

OK, one more comment, then I'll stop. :-)

Does the desktop version do all the math functions of the web/free version? Most EE types aren't too into closing sidebars or color schemes. I guess if I was a student and there was some sort of teaser, like a way to ease the pain of linear circuit analysis, I'd probably buy.

I wonder what other stuff you could add to mess with competing iPhone apps. I'm a Luddite Blackberry owner, so I don't know quite what's out there.

We have plans for more cool EE features, so that's a bonus. Right now it's more general purpose so we could get a nice first release out. Maybe we'll see some traction if we market it more toward engineers.