This lovely guy is the first HP calculator in my collection. I got it used from a member of the calculator subreddit a week ago, and am still getting used to it.

The speed of the HP Prime when graphing is nothing short of impressive. I was amazed by the 10 frames per second 3D plot rotations on the TI-nspire CX II CAS, but the instantaneous rotations and zooms with the touch screen are seamless and smooth. I’m used to seeing graphs get drawn to the screen from left to right since I’ve been playing with them since the early 90s. Even the TI-nspire has a bit of a hiccup when showing a simple graph. The Prime, though? Immediately shows the graph without hesitation for simple things. It does bog down when you start to push it, but it is still the fastest graphing calculator I’ve ever seen by far.

Given that it graphs so quickly, I was surprised at how slow it is when it comes to some things. sum((e^sin(atan(x)))^(1/3), 1, 1000) took three times longer on the HP Prime than it does on the Casio CG-50, which just blew my mind.

The other thing that I’ve found interesting is it’s lack of precision and accuracy in non-CAS mode. Pop it into degrees mode and run arcsin(arccos(arctan(tan(cos(sin(9)))))-9, which should equal 0. Unless your calculator evaluates the function symbolically, there will always be some residual number due to the way that it performs the calculations. The smaller the number, the more digits your machine keeps track of internally. The best of my current collection is the Casio fx-991CW, which gives an astoundingly small 7.5528x10^-18. The only calculator that I know of that can beat it is the SwissMicros DM-42. The Prime delivered an answer of -1.35733x10^-6, which is about the same margin of error as my Catiga CS-121, or the Casio fx-115W from the mid-90s.

I haven’t had much of a chance to really play with the CAS yet, but I have found that it will actually handle symbolic sums. That’s something that neither the TI-nspire CX, nor the Casio fx-CG500 can handle at all.

I’m still figuring out where this beast will fit into my day-to-day, but I am quite pleased with it so far!