Selecting only half a row of an array

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Jay Perks
Jay Perks 2020-9-21
评论： Jay Perks 2020-9-21
Hey guys,
Im fairly new to MATLAB and I'm just having a problem working out how to multiply ony half a row of my array.
I was hoping someone could help me out.
Basic example
a = 1x5
1
2
3
4
5
6
How would I select 2, 3, 4 and multiply it by 3
and how would I select 4, 5, 6 and multiply it by 3

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KSSV
KSSV 2020-9-21
Read about MATLAB array indexing, instead of asking very simple basic questions.
If a is an narray of size 1x5.
a(1:2) % gives first two arrays
a(1) % gives first
a(end) % gives last element
a(2:4)
iwant = a(1:3)*3 ; % pick first three and multiply by 3
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KSSV
KSSV 2020-9-21
BA = zeros(201,1) ;
BA = cosd(DOMAIND); % BA = 201x1
BA =BA(101:201,1).*-1; % BA = 101x1
Jay Perks
Jay Perks 2020-9-21
Thanks KSSV!
In the end I used the below command to keep my 201x1 array without it changing to 101x1.
BA(101:201,1) = BA(101:201,1).*-1
Thankyou!

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