HP 50G Arrived Today

[Wes Loewer]

(01-29-2014 06:02 AM)MathyTortoise Wrote:  Matrices are absolutely maddening. Even if I master my HP 50G, and 48G I guess, I will never approach doing matrices with anything other than my TI-nspire; no other calculator is faster for input.

The Nspire has its strengths and weaknesses. I'm not putting it down (to each his own), but I'm curious about what you meant by faster input for matrices. In fact, matrices are one area in which I find the Nspire particularly inefficient.

For simple things, the 50g takes slightly fewer keystrokes (I'm including shifts). For example: entering and inverting a 4x4 matrix of single digit numbers. The most efficient ways I could come up with were the following. (I'm sure others can come up with slightly more efficient steps, but these will be close.)

Nspire using template: 41 keystrokes
Nspire using [[]]: 47 keystrokes
50g using Matrix Writer: 39 keystrokes
50g using [[]]: 37 keystrokes

When it comes to more involved matrix tasks, I find the Nspire's menu system almost unbearable. Say you were given a 3x4 augmented matrix and were asked to put the matrix in Row Echelon Form, showing each step (ie, not just using the ref() function).

Starting with the random matrix
[[ 4 9 -6 2 ]
[ 6 -9 9 -4 ]
[ -1 -9 4 -9 ]]
I would do the following:

• swap R1 and R3
• add 6*R1 to R2
• add 4*R1 to R3
• add -27/63*R2 to R3
• mult R1 by -1
• mult R2 by -1/63
• mult R3 by -7/29
  

to get
[[ 1 9 -4 9 ]
[ 0 1 '-11/21' '58/63' ]
[ 0 0 1 '64/29' ]]

Assuming the matrix is already on the history stack.
Nspire: 96 keystrokes (assuming not already in Matrix menu)
50g: 52 keystrokes (assuming not already in Matrix menu)
50g: 46 keystrokes (using CUSTOM menu)

For the Nspire, I used the menu system. It may have saved a few keystrokes to type out some of the command names. Even so, the Nspire doesn't come close to the efficiency of RPL and SOFT menus.

I had a student who saw me doing vector (1d matrix) calculations one day in physics class. He was blown away by the way I could do some of the calculations in just a keystroke or two using redefined keys and a CUSTOM menu. He came back the next year with a 50g in hand.

I suspect your tendency toward the Npsire for matrices may be more a matter of familiarity. If that's what you feel most comfortable with, then use it. Be forewarned that once you get the hang of doing matrices on the 50g, you may find your Nspire feeling lonely and jealous. :-)

-wes