HP50g can't handle some matrix products
Merciadri Luca
Hash: SHA1
Hi,
My HP50g is unable to multiply a 1 by n vector by a n by 1
vector. However, matrix dimensions agree for the product, and this
product is thus defined. This is even the definition of the scalar
product of two vectors when their components are given.
Is it normal? Is there a way to make this scalar product?
Thanks.
- --
Merciadri Luca
See http://www.student.montefiore.ulg.ac.be/~merciadri/
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Life is like a box of chocolate, you never know what you're gonna
get.
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TW
> vector. However, matrix dimensions agree for the product, and this
> product is thus defined. This is even the definition of the scalar
> product of two vectors when their components are given.
One is a vector, the other is a matrix. They are two different types
to the calculator. Make sure they are defined both with [ [ 1 2
3 ... ] ] as opposed to just [ 1 2 3 ... ]. It should work then I
think.
TW
Merciadri Luca
Hash: SHA1
TW <timwe...@gmail.com> writes:
Okay. But a question then arises: why is a such a vector matrix not
defined as a vector, simply?
Thanks.
- --
Merciadri Luca
See http://www.student.montefiore.ulg.ac.be/~merciadri/
- --
The exception proves the rule.
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MACH
wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> >> My HP50g is unable to multiply a 1 by n vector by a n by 1
> >> vector. However, matrix dimensions agree for the product, and this
> >> product is thus defined. This is even the definition of the scalar
> >> product of two vectors when their components are given.
>
> > One is a vector, the other is a matrix. They are two different types
> > to the calculator. Make sure they are defined both with [ [ 1 2
> > 3 ... ] ] as opposed to just [ 1 2 3 ... ]. It should work then I
> > think.
>
> Okay. But a question then arises: why is a such a vector matrix not
> defined as a vector, simply?
>
> Thanks.
> - --
> Merciadri Luca
> - --
>
> The exception proves the rule.
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> Version: GnuPG v1.4.9 (GNU/Linux)
> Comment: Processed by Mailcrypt 3.5.8 <http://mailcrypt.sourceforge.net/>
>
> iEYEARECAAYFAk2HXdMACgkQM0LLzLt8MhyT7gCZAVXmel6ay+SngTgO2oXhHhQ1
> myEAoJo1oksJr0eslofyBb76pt+cTg0g
> =eMiJ
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Hi!, Merciadri:
Have you seen the following video? ... http://www.youtube.com/watch?v=g-pO8X8k8pg
Best Regards.
MACH.
John H Meyers
> My HP50g is unable to multiply a 1 by n vector by a n by 1 vector.
There is no such thing as a "1 by n vector" vs. an "n by 1 vector,"
because a "vector" is a ONE-dimensional LIST of 'n' values,
which has no "second dimension."
The only legitimate types of "vector multiplication"
defined in HP graphing calculators are:
[ 1 2 3 ] [ 4 5 6 ] DOT @ Result: 32
[ 1 2 3 ] [ 4 5 6 ] CROSS @ Result: [ -3 6 -3 ]
A Matrix, on the other hand, is a TWO-dimensional array,
and there is a significant different between these examples:
[[ 1 2 3 ]] @ "1x3" matrix (one row)
[[ 4 ] [ 5 ] [ 6 ]] @ "3x1" matrix (one column)
Valid products of these are highly dependent upon the order of multiplication
(or to put it another way, which "vector" to treat as a "one row matrix"
vs. the other "vector" being treated as a "one column matrix"):
[[ 1 2 3 ]] [[ 4 ] [ 5 ] [ 6 ]] * @ [[ 32 ]]
[[ 4 ] [ 5 ] [ 6 ]] [[ 1 2 3 ]] * @ [[ 4 8 12 ] [ 5 10 15 ] [ 6 12 18 ]]
As a special case, the calculators accept:
[[ 1 2 3 ]] [ 4 5 6 ] * @ [ 32 ]
Where a vector 2nd argument of "*" is treated as a 1-column matrix,
and the one-column matrix result is again output as a vector;
this is handy to save a little effort and eye-strain
in representing systems of linear equations as 'A*X=B'
where 'X' and 'B' may each be represented as vectors,
rather than as one-column matrices.
[r->] [OFF]
Virgil
Merciadri Luca <Luca.Me...@student.ulg.ac.be> wrote:
> Hi,
>
> My HP50g is unable to multiply a 1 by n vector by a n by 1
> vector. However, matrix dimensions agree for the product, and this
> product is thus defined. This is even the definition of the scalar
> product of two vectors when their components are given.
What is mostly displayed as row vector, such as [ 1 2 3 ] is treated
internally, as are all vectors, as a column vector so that [[1 2 3 ]]
times [1 2 3] in that order is a proper operation , a 1 by 3 matrix
times a 3 dimensional column vector and results in [ 14 ], a one
dimensional vector.
Whereas [1 2 3] times [[ 1 2 3 ]] in that order is improper and results
only in an error message.
If vectors were required to be matrices, then the vector [`1 2 3]
would be have to be [[1] [2] [3]] rather than [[1 2 3]].
So the hp50 does handle those matrix products, one you understand the
peculiar vector notation of displaying internally held column vectors as
if they were row vectors.
It is just one of those idiosyncracies of the HP48-49-50 series you
have to get used to.
Merciadri Luca
> In article <87r5a0vfq4....@merciadriluca-station.MERCIADRILUCA>,
Thanks all!