The Casio ClassPad II (fx-CP400) is the latest CAS offering from Casio: building on the previous ClassPad model to provide a calculator with a large color screen, and the ability to operate it in landscape or portrait mode.

I acquired one of these babies a few months ago, and should have posted about it then, but didn’t. So here goes.

The first reaction on seeing it was that it was very big. In fact I think this is just a matter of its huge screen: the entire unit is in fact not much bigger than the TI-nspire. Here’s a shot of the two of them (in their protective cases), with a pair of spectacles and a ballpoint pen for comparison (the ClassPad is on the right):

And here with their cases off, ready for action:

The screen is absolutely *gorgeous* – I can’t say enough good things about it. Crisp, well saturated colors, great for things like sketching a function and its derivatives; really beautiful. What else is good about it? Well, here’s where things get a bit tricky: in fact, I can’t really find any.

Here’s a few random comments:

- The system is not much unchanged from the previous ClassPad models. You still have the stylus-driven menus (and very good they are), and woefully underpowered hardware. I did a tiny test: to factorize Cole’s number . Here are some timings:
- TI-nspire: Pretty quick (a few seconds; sometimes longer if the memory’s full)
- Android Maxima (on my Samsung Galaxy S III): almost instantaneous
- Casio ClassPad: a day until it ran out of batteries

- I have long been critical of 3D graphing on the tiny screens of most CAS calculators: but here at last is a screen on which 3D graphics would work very well. But guess what: Casio, in their wisdom, have not included 3D graphing in this system!
- The buttons below the screen are small, plasticky, and feel cheap. Because of their size they wobble a lot. (However, the buttons on the TI-nspire, in spite of comparable size, have hardly any wobble.) The feeling is of a cheap build.

I expect that Casio is aiming fully for the school market. The combination of software and hardware means that this machine would be inadequate for any but the simplest mathematics. I don’t see why this should be so – better programming and a more powerful chip would make this machine into a really useful mathematical tool. As it is I see it as a gorgeous body with not much strength underneath.

I’ve also purchased a casio classpad II I did the same exercise to factor the number of cole (2 ^ 67 -1) and got a score instantly modify only the basic format (appending the decimal calculation)

Sir: Let me get to the point.

I am getting wrong values for the centre of an ellipse, as well as it’s eccentricity, when the equation for the ellipse is given in the general form, that is

Ax^2+Bxy+Cy^2+Dx+Ey+F=0

As an example, 5x^2-8xy+4y^2-6x+2y-5=0 is an ellipse with centre (2,1.75) and eccentricity .97213

The ClassPad II fx-CP400 gives the centre as (0.306,-0.618) and eccentricity as 0.2189. You can see the red cross that is supposed to appear at the centre of the ellipse is way off the mark.

If we rotate the axes, so as to eliminate the xy term, the equation becomes 8.5311x^2+0.46887y^2-5.8216x-2.4714y-5=0; The centre is now at (.3412,2.635); eccentricity is of course the same as before, .97213; and this time, once we have typed in this second equation, the ClassPad gives us the correct values.

It appears the errors occur when we employ the general form of the second degree equation to define the ellipse. When the term in xy is absent in the equation, the results are correct.

I have not looked at the other conics; nor at focus, vertex for the ellipse.

I would welcome your comment.

Adrian Tata (Bombay)

4th February 2014.

I can’t find the programming application on the new colour ClassPad. Did Casio omit this like they did the 3D graphing application? I am really keen to know.

Secondly, your comparison would have greater validity if you used a TI-Nspire CX colour calculator rather than to discontinued TI-Nspire TouchPad.