Using an existing vector in a .M file

Hello! I've made a simple function file and let's say I need to input a vector (50 elements) so that a function gives me the resulting vector for those elements. I have the vector in the workspace but when I try to use it as an input (instead of for example introducing the input like this [1 2 3 4 5... 50]) the vector is not recognised as a valid entry and is as if i hadn't introduced nothing. How could I solve this? Is a problem in the script? I have it as:

P_k='Introduce the 50 values';
P_k=input(P_K);

I'm new into this and I really don't know how can I solve this and hadn't found anything related

[Stephen23]

"I have the vector in the workspace but when I try to use it as an input..."

What does this mean? As "an input" to what exactly? Your example does not generate any error, so it is not clear what problems you are having.

[Eduardo Chacin]

Maybe I'm not explaining myself clearly. I have in the workspace the vector V=[1 2 3 ... 50]. The .M file is called EXERCISE. When I call "EXERCISE" I got the message 'Introduce the 50 values', but when I try to use v (as the input) it shows as if I hadn't introduced nothing (that means... it doesn't recognise the 1 2 3... 50). And I would like to be able to introduce 'v' instead of having to introduce [1 2 3... 50]. Is that possible?

[Stephen23]

"Is that possible?"

That depends on how EXERCISE was written. Is EXERCISE a script or a function?

Note that using input is beloved by beginners, but is really a very ungainly way to interact with code.

[Eduardo Chacin]

Is a function file. How would you do it in a better way?

[Stephen23]

@Eduardo Chacin: change the function to accept input arguments.

For some reason some beginners think that forcing the user to enter everything with input is the best thing since sliced bread. But, as you are finding out now, this just slowly and pointlessly forces the user to interact with the function in just one way: through whatever input prompts they happen throw at the user. This means that it is not possible to call the function efficiently in a loop with different input values, or use it in any optimizing function, or really do anything useful with it at all. In short, input is how some beginners make their functions totally impractical to work with.

The solution is that you should edit that function, get rid of any input commands and replace them with function input arguments, exactly as described in the function help. Then just call the function with the input values that you require. Exactly as all functions should be!

[Eduardo Chacin]

@Stephen Cobeldick Could you show me how please? Better to correct this as I'm a beginner than keeping with it and complicating the interactions.

[Stephen23]

function C = myFun(A,B)
C = A + B;
end

Then call the function with the required inputs:

myFun(pi,0:10)

[Eduardo Chacin]

@Stephen Cobeldick thank you very much

Answer 1

[M]

Does this discussion https://mathworks.com/matlabcentral/answers/1748-storing-user-input-as-a-vector answer your question ?

[Eduardo Chacin]

But that's for storing the input as a vector. I already have the vector and I want to use it as an input.