why gradient and diff return many values?

hello,

I need use the derivatives for example in loss function is J(w,b) such that find

w=w-α * (∂J/ ∂w)

when I used diff or gradient I have many values, In fact I need only one value represent (∂J/ ∂w).

Please, can one help me to provide me with that command.

Thanks in advance

[Jan]

The readers cannot guess, what your inputs are.

[KALYAN ACHARJYA]

More, the result after gradient operator is always vector.

[dpb]

How well it would work or even be reasonable would be entirely dependent upon the problem characteristics but one could try mean(gradient()) to get an average to reduce a vector to one value.

[huda nawaf]

@ Jan

In fact I just need compute the derivative, and I know when compute the derivative for one variable I shoud get one value.

@ KALYAN ACHARJYA

that is mean I did not use the right command. I want to calculate the derivative for one variable respect to functionnd