I intended to post a lot about these calculators over the past few months, but, err… didn’t. Anyway, I’ve been using both extensively (mainly to perform numerical computations), and here’s a few things I’ve found out:

- The ClassPad 330 handles variables far better than the TI-nspire. The TI-nspire does have a menu command for removing all variables with a single letter name, but there’s no easy way to go though a list of variables, check some (or all), and delete or move those selected. The ClassPad provides this functionality.
- The TI-nspire allows programming constructs to be used in a command. For instance, you can use a for-loop to build a list. The ClassPad, however, allows such constructs to be used only within a program. This makes the TI-nspire slightly more efficient to use.
- Neither calculator, as far as I can find, allows you to pull apart an expression into component parts. This is a standard functionality of all CAS’s, and I don’t know why it’s missing here.
- The TI-nspire has some useful matrix commands lacking on the ClassPad. For instance, there’s no way on the ClassPad (other than writing a program) of creating a matrix whose elements are functions of the row and column indices. The ClassPad also lacks commands for pulling out the diagonal elements of a matrix. And curiously enough, given an matrix and a column vector , the ClassPad lacks a command for solving the matrix equation . You can of course compute , but that’s it.

Both calculators lack various functionality present on the other, and so weighing one against the other they’re pretty even. Both have room for improvement (I’m looking forward to seeing the new whizz-bang all-singing all-dancing FX CP-400 when it reaches our shores in a few months). I personally find the TI-nspire slightly faster and easier to use.

Finally – why a calculator? As a few correspondents have pointed out, you can get (if not now, then soon), much of the same functionality on a smartphone or tablet – and indeed TI have produced an app version of the nspire – so why buy a calculator which does only one thing, when for only a little bit more you can buy a tablet which does all of that and more?

Part of the answer lies with education: you can easily allow a calculator in a test or exam – and change the mode of questions to be more method focused than answer focused – when you would never allow a tablet (at least, I can’t think of any testing milieu which would allow a tablet). Also, calculators are easier to use than any tablet, at least for maths. You can enter a complicated expression such as:

very easily on a CAS calculator by pressing only a few keys; whereas on a tablet such an expression may mean hunting through different menus to obtain all the symbols you need.

Calculators also tend to be more robust than tablets; they can survive being tossed around in bags and pockets without requiring after-market protection or care (both the TI-nspire and ClassPad come with hard covers as standard.) And because of the small screens, they use less power. So a student (or anybody else) can bung a calculator into their pocket or bag, and have it ready to use whenever they want.

For these reasons I still think calculators have a place.

I am writing parallel TI nspire and ClassPad instructions for a couple of organisations. I have run into a problem with the Classpad’s inability to solve equations containing factorials, eg solve(nCr(7,r)=21,r). The Classpad seems incapable of solving or even simplifying equations and expressions containing factorials. Do you have any suggestions?

O

ne more question. Can the ClassPad do anything remotely similar to a TI nspire slider?

Thanks,

Neale Woods

Melbourne, Australia

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Be sure of your facts before making statements comparing calculators. On a TI nspire on Calculator page, press menu > Actions > Delete Variable to remove a variable. Press the var key to display the list of variables to select from. You also have the option of menu > Actions > Clear a-z to remove all single letter variables in one step. Unlike a ClassPad, if you start a New Document, you don’t have to worry about any previously defined variables. I find these often get in the way of subsequent calculations on a ClassPad if I don’t specifically remove them.

Just a note regarding the parsing of expressions. The TI-Nspire actually does have a CAS command for this called “part” which appears to be undocumented. It breaks any appropriate expression into 2 parts: so part(x^2-4x+3,1) = x^2-4x and part(x^2-4x+3,2) = 3. A little nesting readily produces the terms of a given expression.