How to Find Number of Rows

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How do I get 3 ?

 

 

 

 

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Thats easy - you get 3 if you use a vector or matrix with just three rows. 😉

But the vector M you created has six elements for reason which Terry already explained.
So its correct to say that has six rows.

Give it a try yourself and type M=  You will see a six rows vector.

BTW, when you try rows(i) or rows(M[i) you feed the elements 3,4,5 one after the other in the rows() function. Each of these values is a scalar, not a matrix or vector and so the row() function returns 0 for every of these three values and thats the reason for the vector with three zeros you get as a result.

If you want to create a three element vector with the values 3,4,5, here is the way to go

You could also do it that way

but I would recommend the first approach.

You may even do it that way

but I would strongly advise against it.