Obtain coordinate of a vector or multivalued function

1.Given a vector v (with some number of coordinates) obtain its i-th coordinate.

What is the command for this? I'm expecting something like v[i]

2.Same question but with a function with multiple outputs, for example:

f=@(a,b,c,d) [a^2-b+c+d,a-b^2+c+d^3,a*b*c*d,a-b-c-d]; (in general a function created like this from m inputs to n outputs)

to obtain say the third coordinate of f(w,x,y,z) I would expect something like f(w,x,y,z)[3], what is the command?

Both could be the same question if the second is also a vector but I don't know how to check that.

Answer 1

[KSSV]

It should be v(i) not v[i]. Read about MATLAB indexing.

f=@(a,b,c,d) [a.^2-b+c+d,a-b.^2+c+d.^3,a.*b.*c.*d,a-b-c-d]; % anonymous function. Read about this
a = rand(10,1) ;
b = rand(10,1) ; 
c = rand(10,1) ; 
d = rand(10,1) ; 
f = f(a,b,c,d) ;
for i = 1:10
    f(i)
end

ans = 0.1073

ans = -0.1436

ans = 0.4184

ans = 1.7885

ans = 0.7335

ans = 1.2884

ans = 0.2352

ans = 0.7480

ans = 1.8433

ans = 1.1062

[Josephine A]

I see. It is not possible to just say f(w,x,y,z)(3), one has to store it in a new variable like k=f(w,x,y,z) and then say k(3). Thanks!

[KSSV]

You can use:

f3 = f(a(3),b(3),c(3),d(3))