# Vector Space

There are a number of examples in the text that today’s lecture expects you to type in and practice. If in future, you do not know how to program, it will be because you were lazy in simply typing in code and running them. “The fault, dear Brutus, is not in our stars,

But in ourselves, that we are underlings.” A word enough for the wise!

There is a test next week on Chapter One. Those who refuse to practise are going to have a cold shower on a harmattan morning!

Good day sir, please how can we access the textbook?

Find it here

Good day sir,

page 70 solved problem 1.3

according to the tell tale signs

A dummy index must occur twice. But it DOES NOT have to occur in another term.

but in the solved problem we have

× = k

a*b = eijk aj bk ek

i know from Vector Product in Component Form that

× = k

ei * ej = eijk ek

aj is correct also but the bk i think it should be bi and not bk.

i dont know if am the one getting it wrong but according to the tell tale sign if am to solve that problem the results would be

a * b = eijk aj bi ek

the tell tales sign 3 made a *b = eijk aj bk ek wrong to me dont know if it is correct sir.

or a*b = ejik aj bi ek

Eniola, it is a typo error.

It should read a×b=eijk aj bk ei

Dr Adewumi’s comments are correct. The text will be corrected.

from solved problem 39 the result of ⋅ ( ⊗ ) is a vector.

from solved problem 40 the result of × ( ⊗ ) is a tensor.

I don’t understand how this was simplified to result in a vector and tensor respectively.

from solved problem 39 the result of u ⋅ (v ⊗ w) is a vector.

from solved problem 40 the result of u × (v ⊗ w) is a tensor.

I don’t understand how this was simplified to result in a vector and tensor respectively.

The first expression, when fully expanded in component form is the same as (w⊗v)u which is obviously a vector. The tensor nature of the second expression will become more obvious to you when we are deep into the next chapter.

Good Morning sir,

Tried the mathematica codes on page 12 and kept getting error

First no arrow automatically appeared after typing Plot range and Ticks but was able to bypass that with a cut and paste trick collecting arrow from Plot Style But it still didn’t run.

It said

Visualisation’Core’ParametricPlot3D: –Message text not found — ({1, y, z, Null})

General : further Output of Visualisation’Core’ParametricPlot3D::invfuncs will be suppressed during this calculation

And so many more

To give me a copy of your code so I can see your problems is doable. We are NOT at that point yet. The way to type in the arrow is to follow the minus sign with > (the “greater than sign”, above the period sign). You are at the first step of simply copying my working code and getting the pain of executing it while hunting down your typos. I have typed the code in just now without changing anything. It works just fine. I will urge you to go back again and compare what you typed to what was given. The code works fine!

Solved problem 1.16,page 78… Anybody can help with how they got to the next step of the solution(the part I wrote the note)

1.16 Show that ( × ) ⋅ ( × ) × ( × ) = ( × ⋅ )^2

( × ) ⋅ ( × ) × ( × ) = ( × ) ⋅ [( × ) ⋅ ] − ( × ) ⋅ [( × ) ⋅ ]

I don’t really get Wat happened here….seems to me like a part of the equation was just taken

= ( × ) ⋅ [( × ) ⋅ ]

= ( × ⋅ )(( × ) ⋅ )

= ( × ⋅ )( ⋅ × )

= ( × ⋅ )^2

Nice content

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