Matrix

[resolved]

I don't know if this is the proper use of matrixes, but I put six vectors in one matrix and just wanted to sum the results by column instead of creating six vectors and summing them individually. Is there anyway to just sum the columns?? I could not find anything in the 616 page manual dealing with this.

also in terms of making the HP Prime more user friendly, HP needs more useful Error messages. Example: I tried to store a matrix under the name 'A' but got an error message, “Error: Bad argument type,” which means nothing to me other than I made a mistake. I read the manual, I tried a plain A, I tried an A within single quote marks, I tried another letter. Nothing worked until I tried using 2 (TWO) alphanumeric symbols, then I was able to store the vector. Nowhere, that I could find, in the manual does it said that two or more symbols are required to store a matrix. A useful message would be “Error: naming matrixes requires two or more alphanumeric symbols,” which would save the user twenty minutes of frustration.

Is there any symbol one can use to speed up the entry of dot and cross products, another than what is given in the manual, ie DOT(,), CROSS(,)???

If I make a mistake and add another row to a vector and then delete that mistake so that I only have one row and then store that vector, it gets stored as a matrix and I can not use that vector for any further vector analysis. I then have to start all over again rewriting that vector saving it to over write the prior saved vector/matrix. It seems to me that this is a bug, one row should be saved as a vector not a matrix, even though one made a mistake upon entry.

[parisse]

Inside CAS:
m:=[[44,48,82,48,55],[-65,-20,72,-86,-16],[77,-46,-28,-28,23],[-26,-46,-87,88,6],[-16,14,69,71,-78],[-74,81,-27,-87,81]];
sum(m);
You can use lowercase one letter names for any kind of variable in CAS.
Also * does dot product inside CAS

[resolved]

thanks parisse, that worked, but I still get confused as when to use capital letters or small letters for commands… sum(a1) works; SUM(a1) doesn't.


Also I encountered another problem with my HP Prime when scrolling up or down the matrix menu, after an undetermined number of button clicks (some times 7 clicks, 12, or 5 clicks will do it) the calculator turns itself off and restarts. Is this a bug or is it intended? If intended what is its purpose?

[resolved]

Sorry, I was not very clear when I said "matrix menu" What I meant was, when going into the "Memory Manager" and then clicking into Matrices, when I click down the menu after 21 clicks the calculator reboots. This did not happen in Notes after 50 down clicks… When in the Matrices Memory Manager, sometimes as few as five clicks have reset the calculator….

[dbbotkin]

(08-07-2014 07:04 AM)parisse Wrote:  Inside CAS:
m:=[[44,48,82,48,55],[-65,-20,72,-86,-16],[77,-46,-28,-28,23],[-26,-46,-87,88,6],[-16,14,69,71,-78],[-74,81,-27,-87,81]];
sum(m);
You can use lowercase one letter names for any kind of variable in CAS.
Also * does dot product inside CAS

Entering the matrix above was (for me) not intuitive: I tried using the '[]' key without success to enter the '[[44,48 . . .],[ . .'.

The way that worked for me was 'm:=[44,48,. . .],[-65,-20, . . . etc.' and then 'Enter' the put the [[...]] matrix on the stack. Whew!

The 'sum()' function worked as stated.

I got the same result for 'sum(m)' with the data in a 6x5 matrix.

Very nice!

[parisse]

You must select algebraic entry instead of textbook to enter matrices with the notation I used ([ [...,...],[...,...],... ], a matrix is a list of lists of the same size). This is the 1-d analog to the 2-d templates on the Prime. 2-d entry is more intuitive, but 1-d text entry has a advantage: you can copy/paste the text everywhere, for example in Xcas, or any compatible CAS.