access elements of a vector output in one line

say I have some function output = f(vars), and output is a vector. how can I, in one line, access elements of this vector?

example:

What I want is M and then to plug it into sin(x), the traditional way:

A = ones(2,3);
[M,~] = size(A);
s = sin(M);

An Idea of what I want:

s = sin(size(A){1})

parenthesis gives the result of the function, and the hypothetical curly brackets would return the first element of the result of the function.

Answer 1

[Azzi Abdelmalek]

s = sin(size(A,1))

Or you can do it this way

s=sin(size(A))*[1;0]

Answer 2

[Walter Roberson]

IndexAt := @(V, varargin) V(idx, varargin{:});

Then

IndexAt(size(A), 1)