Access to the components of a vector

This issue is particularly well treated in the documentation of Scilab perhaps because it constitutes the core of the access to the matrix structure. We are going to introduce only some features.

Let's define a vector

-->stepvector = [zeros(1,5), ones(1,5)]
 stepvector  =
 
!   0.    0.    0.    0.    0.    1.    1.    1.    1.    1. !

`zeros(n,m)' produces a matrix of n rows and m columns or zeros, `ones(n,m)' does the same with ones, the `comma' chains both in rows and the brackets build the vector.

To extract its individual components we can use the next commands

-->stepvector(5)
 ans  =
 
    0.  
 
-->stepvector(6)
 ans  =
 
    1.  
 
-->stepvector(4:7)
 ans  =
 
!   0.    0.    1.    1. !

We can eliminate some components

->length(stepvector)
 ans  =
 
    10.  
 
-->stepvector(4:7)=[]
 stepvector  =
 
!   0.    0.    0.    1.    1.    1. !

-->length(stepvector)
 ans  =
 
    6.

Or we can insert some new components

-->stepvector = [stepvector(1:3), [2,2,2,2],stepvector(4:6)]
 stepvector  =
 
!   0.    0.    0.    2.    2.    2.    2.    1.    1.    1. !

To access the last component of a vector we could do

-->stepvector(length(stepvector))
 ans  =
 
    1.

But we also have an interesting operator: `$'

-->stepvector($)
 ans  =
 
    1.

which enables to select elements from the end

-->stepvector($-4)
 ans  =
 
    2.

We have extracted, inserted and deleted internal values of a vector; now we are going to use these methods for some practical objectives.