The Dream Team

Changy

Hello there:

My name is Changy and my logo is the well familiar

<=>. My job is to interchage rows. I shall typically appear on the screen as follows:

R_{i}<=> R_{j}which is short-hand for "interchange row i and row j".

The people responsible for this place decided to implement me with the aid of two columns of radio buttons, which appear on both sides of the matrix you'll be working with . Thus, you shall have to specify the pair (i,j) using these buttons. I am happy with this arrangement and I do hope that you'll find it user-friendly.

You may wish to practice me a bit now.

Timy

Timy is my name. It is a pleasure meeting you.

Consistent with the long and well established tradition in this business, I do not have a logo! What a shame! What I do for living is this: I multiply rows of matrices by scalars. For example, in the expression

R'_{2}= (3/2)R_{2}I multiply the second row of a matrix by 3/2, namely I multiply each entry in the second row of the matrix by 3/2.

On the screen I shall appear as follows:

R'_{j}= a R_{j}where j represents the row I multiply and a represents the scalar I use. I have no complaints regarding this arrangement, I have been working with a on many other occasions and I am confident that we shall manage just fine.

Now, to use me you'll have to specify two things:

- The row I should operate on
- The value of the scalar a I should use.
As my colleague Changy already indicated, the Management of this place is using radio buttons to specify the rows of matrices. Thus, you shall have to use a radio button to specify the row I should operate on. Please note that there are two columns of radio buttons and that when you communicate with me you'll have to use the buttons on the right-hand side of the matrix.

Regarding specification of a, you'll be provided with an input form, located between me and my colleage Addy. You cannot miss it.

Bear in mind the following points when you specify the value of a :

- For various reasons Management does not accept decimal fractions - so please use proper fractions.
- Management does not accept 0.
I suggest that you practice me now.

Addy

I am Addy

I work in close cooperation with Timy. My job is to add to a given row of a matrix the results of the product of another row of the matrix with a given scalar. For example, in the expression

R'_{2}= R_{2}+ (-3/2)R_{3}I am adding to the second row of a matrix (-3/2) times the third row of the matrix.

On the screen I appear as follows:

R'_{i}= R_{i}+ a R_{j}To use me you'll have to tell me the row you want to modify (i), the value of the scalar I should use (a) and the row I should multiply (j). The arrangements made for inputing the scalar a are the same as those described by my colleague Timy. The two rows are specified by the radio buttons: the row you want to modify is pecified by the radio button on the right-hand side of the matrix and the row you want me to multiply is specified by the left-hand side button.

It is a straight forwarded procedure. Try it!

Pivorrratti

How are you?

I am the beloved Pivorrratti - yes the one and only one! The

~~opera~~operation I am responsible for, namely pivoting, is too difficult to describe in a non technical manner so I shall not even try. If you do not know what "pivoting" is all about you should visit ROWPS Induction Center.Unfortunately, there is no universal logo for my operation. What a pity! Consequently, on the screen I shall appear as Pivot(i,j).

To instruct me on what entry of the matrix I should pivot, use the right-hand side radio buttons to specify the row (i) and the radio buttons at the bottom of the matrix to specify the column (j). Leave the rest to me!

Management asked me to advise you that no pivoting on zero entries will be allowed on our premises.

You are coordially invited now to practice your pivots.