Cross in Matrix

10152014, 06:52 PM
Post: #1




Cross in Matrix
How i can input a matrix and have a cross product?
ex. i j k 2 3 1 1 2 3 and i need a det. solution: 1i + 2j +3k my hp prime say error when i input Cross( M1 ) M1= i j k 2 3 1 1 2 3 in hp50g is easy but here 

10152014, 08:48 PM
(This post was last modified: 10152014 08:51 PM by Han.)
Post: #2




RE: Cross in Matrix
cross() takes two vectors and computes the cross product; one way to do this is to compute the determinant of the matrix you described. So if you already have the matrix, you want to use the det() command
So either use: cross([2,3,1],[1,2,3]) to get [7 5 1] or use \[ \mathrm{det}\left( \left[ \begin{array}{rrr} i & j & k \\ 2 & 3 & 1\\ 1 & 2 & 3 \end{array} \right] \right) \] to get \( 7\vec{i}  5\vec{j}+\vec{k}\) Graph 3D  QPI  SolveSys 

10162014, 01:48 AM
Post: #3




RE: Cross in Matrix
Handling matrixes is more efficient in the Prime than in the 50g.
I recommend you to use CAS and the matrix templates. Put the command and then manually enter the matrix using the matrix template (1st row, last column). The comma button serves as a "next column". This is very helpful to solve linear system of equations too (inverse coefficient matrix * contant matrix, RREF command, etc). After a couple of minutes, you will see how efficient the Prime is with matrixes thanks to the big touchscreen. 

06232015, 01:59 AM
Post: #4




RE: Cross in Matrix
Why does
det( [ [ i j k ] , [ 2 3 1 ] , [ 1 2 3 ] ]) return 6.48*j+2.04*k0.24*i instead of 0.24*i6.48*j+2.04*k 

06232015, 12:27 PM
Post: #5




RE: Cross in Matrix
(06232015 01:59 AM)rgallier Wrote: Why does "i" is always put at the end because "i" is not a variable, but is the constant i. Try h+i+j; it returns h+j+i. Never use i or e as variables, because they aren't. <0ΙΈ0> Joe 

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