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#1 2010-07-18 12:20:42

samuel12
Member
Registered: 2010-07-17
Posts: 19

linear algebra

just a quick question and sorry for being messy =/

[    1                2              3        ...          n   ]                                     
[  n+1            n+2          n+3      ...         2n  ]                           
[ 2n+1          2n+2         2n+3     ...         3n  ]                       
[   .                                                         .   ]                                         
[   .                                                         .   ]                                         
[   .                                                         .   ]
[(n^2 -n +1)(n^2 -n +2) (n^2 -n +3) ... n^2  ]

I am asked to find the row echelon form of the nxn matrix.
What i did is minused n from row 2 then minused 2n from row 3 and so on... untill the last row where i minused (n-1)n

this gave me an nxn matrix with identical rows containing 1 2 3 ... n     

Would this be sufficent as the row echelon form of the matrix or simplify it further?

Thanks in advance for the help smile

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#2 2010-07-18 12:54:03

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: linear algebra

Hi samuel12;

Did you try your idea on a 4x4 matrix as a test?

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#3 2010-07-18 13:04:52

samuel12
Member
Registered: 2010-07-17
Posts: 19

Re: linear algebra

yeah i think i got a bit confused=/ let me get back to you haha

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#4 2010-07-18 16:35:44

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: linear algebra

Hi samuel12;

No problem.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#5 2010-07-20 08:56:08

samuel12
Member
Registered: 2010-07-17
Posts: 19

Re: linear algebra

Umm i'm not going to bother posting what i got unless anyone actually wants the answer smile if so speak up.

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#6 2010-07-20 15:35:57

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: linear algebra

Hi samuel12;

The answer! I don't even know what the question is. Better start with that!

I see what you are saying! It's for the nxn matrix that you want the rref of. Post what you have discovered, I will look at it. I can't guarantee I will understand it!

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#7 2010-07-20 16:32:06

samuel12
Member
Registered: 2010-07-17
Posts: 19

Re: linear algebra

the first row operation will be...

minus R1 from each of  R2 through to Rn

then

divide all rows from R2 through to Rn by n

then

minus (n-1)R2 from each R3 to Rn (where n is the row number i.e. a constant)

now finally R2 - R1

to get....

[1 2 3 ... n]
[0 -1 -2 ... 1-n]
[0 0 0 ... 0]
[0 0 0 ... 0]
etc etc

which is the given nxn matrix in row echelon form (i think haha)

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#8 2010-07-20 19:25:53

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: linear algebra

Hi;

now finally R2 - R1

Do I store R2-R1 back into R2?

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#9 2010-07-22 22:25:39

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: linear algebra

Hi easycalculation;

Some nice calculators there but no biorhythm one.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#10 2010-07-23 15:28:26

samuel12
Member
Registered: 2010-07-17
Posts: 19

Re: linear algebra

Hi;



now finally R2 - R1

Do I store R2-R1 back into R2?

Umm yeah so like R2---> R2 - R1

if that makes sense=)

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#11 2010-07-23 16:22:35

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: linear algebra

Hi;

No like R2-R1 -> R2

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#12 2010-07-25 11:27:25

samuel12
Member
Registered: 2010-07-17
Posts: 19

Re: linear algebra

Well yeah different notation in different countries i guess haha

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