Matrix Cross Product on a HP 50g

[Selah]

I am trying to do a Cross Product of a vector.

-30k

0.1i + 0.173j

When I input this into matrix writer and then choose cross product off the VECTOR - CROSS menu, I get "Cross Error: Bad Argument Type".

What am I doing wrong?  I have tried to look through the manual and it isn't much help.

Thanks!

[BartdB]

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Selah wrote:

I am trying to do a Cross Product of a vector.

-30k

0.1i + 0.173j

When I input this into matrix writer and then choose cross product off the VECTOR - CROSS menu, I get "Cross Error: Bad Argument Type".

What am I doing wrong?  I have tried to look through the manual and it isn't much help.

Thanks!

---

Hi,

For the Cross Product of vectors, you need two vectors.

If your screen looks like this:

Then it is a single matrix (noted by the thick lines of the square bracket). Cross product does not work on matrices.

Also the vector must have at least 2, but no more than 3 elements. If those are 2 vectors you are showing, they have only one element.

"Attempts to calculate a cross product of vectors of length other than 2 or 3, produce an error message"

i.e. the following will work:

[-30k    0]

[ 0        0.1i + 0.173j]

CROSS

= [0     0       (0.1i+0.173j)*(-30k)]

Regards

Bart

[Selah]

How are you able to input

[-30k 0]

into the calculator?  When I try to put -30k into the matrix writer, it puts it into two columns.

[BartdB · Accepted solution]

Hi,

Enter it in single quote marks (on the MTRW button), i.e.:

'-30*k'

Also note that when you want to enter vectors in the Matrix Writer, be sure to check the VEC selection:

(note block next to VEC)

Otherwise the calculator will interpret it as a matrix, even if it only has one row (you will see thick brackets instead if thin ones).

This is a matrix:

and this is a vector:

Regards,

Bart

[Jon-Cunha]

Hi,

Can i do a cross operation with unknows, like

[1 2 3] X [A B C], maybe saying do the calculator that A,B,C are variables i do no,

because i´m needing to do that, and only know

to do the vectoral product with two vectors that don´t have unknows.

Thanks. 

[BartdB]

Hi,

Yes, you can do that.

First note that the variables (A, B & C in your example) must not exist as user variables, otherwise the calculator may attempt to substitute the saved values into them when doing operations (this is true for many symbolic operations).

Enter the two vectors:

note the use of  ' '  for alpha characters (use  button).

the go to White Shift - MATRICES, and select VECTOR then CROSS

This will give the cross product:

You can now save this in the user durectory, e.g. 'VEC1' STO

If you now store values in A, B and C you can get a numerical answer by recalling the vector and pressing Orange Shift ->NUM (on ENTER key).

Doing this in ALGebraic mode:

First select White Shift - MATRICES, and select VECTOR then CROSS

Enter the vectors, using the , as separator:

The result will be shown whne you you enter:

HTH