Take 1st and 2nd Derivative of Data Points

I am having issues taking the derivative of experimental data. I have a vector (data_out) that is 2000x1 with experimental data inside. I want to take the 1st and 2nd derivative of this data with respect to a time vector (time) that is 2000x1. I've tried using gradient and diff functions in matlab but I have been unsuccessful.

[Guillaume]

but I have been unsuccessful.

because...?

If you get an error message then give us the full text of the error message (and the code that caused that error)

If you get results different than what you expected then what did you expect and what did you get.

[Daniel Koziel]

Code:

1stD = diff(data_out,1)./diff(time,1);

Error:

Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax error. To construct matrices, use brackets instead of parentheses.

[Alex Mcaulley]

1stD is not a valid name for a variable. From Matlab documentation:

Valid names begin with an alphabetic character, and can contain letters, numbers, or underscores

[Nadir Altinbas]

Data should be in matrix form and then matrix regular operations apply

Answer 1

[Rohit Garud]

You can use the gradient() function

data_first_d = gradient(data_out(:)) ./ gradient(t(:))
data_second_d = gradient(data_first_d(:)) ./ gradient(t(:))