Slightly different issue. Entering equations quickly and accurately is very hard with a virtual keyboard. I'd like to use my phone rather than a calculator in situations when i dont have a full pc handy. I've used Maple extensively and it's a great tool. But I'm not looking for a pc replacement, I'm looking for a calculator replacement. The app side could certainly work like Maple or Mathmatica.

So you are willing to carry around a full mechanical keyboard to attach to your phone and type complex equations, but you can't carry around a netbook or something for that purpose?

I have to say, I'm a little baffled. Phones are for phoning. Computers are for computing.

Smart phones are computers that are capable of phoning too. Netbooks and laptops aren't ideal for entering a lot of numbers either because they don't have a numeric keypad. Calculator keyboards are laid out better for working with equations.

Let me put it another way - do you think calculators are completely redundant?