How can I extract the first element of a vector in simulink?

I have a [1500x1] vector in simulink. I wish to extract the first element from this vector. I have attempted to use a MATLAB function block to perform this task, but it yields me nothing.

Answer 1

[Honglei Chen]

You should be able to use a Selector block. You can find the reference page at

https://www.mathworks.com/help/simulink/slref/selector.html

HTH

[Ziad Almalak]

Excuse my lack of knowledge, but I've tried to configure the parameters of the selector block the right way, and I get the following error:

Error in port widths or dimensions. Input port 1 of 'HLDV4/HLD Vector Subsystem/Selector' is a [?x?] matrix.

If my input is [1500x1] vector, and I intend on extracting element [1x1], what should my selector block parameters be configured to?

[Honglei Chen]

Looks like although your output is 1500x1, it is configured as a variable size signal. I would set it as

• Number of input dimensions: 2
• Index mode: one-based
• 1 -> Index Option: Index vector (dialog) -> Index: 1
• 2 -> Index Option: Index vector (dialog) -> Index: 1

HTH

[Michael Hodgson]

Can I use a Selector block to get the last element of an array? As in, "A[end]"?