# How to find the derivative of a function in Octave

In this guide I'll explain how to calculate the derivatives of a function in Octave.

To calculate the derivative you have to use the command **diff()
**

**diff(function, variable, order)**

The first parameter is the expression of the function, the second is the derivation variable, the third is the order (first derivative, second, third, ...).

**Note**. To use this command you must first have Symbolic installed on Octave.

I'll give you a **practical example**

Define the variable x symbol

syms x

Now calculate the **first derivative** of the function x^{3}+x^{2}+x using the function diff()

diff(x**3+x**2+x,x,1)

**Note**. In the expression, the symbol for exponentiation is **

The result is the first derivative of the function.

ans = (syms)

3⋅x^2 + 2⋅x + 1

Now calculate the **second derivative** of the same function.

Rewrite the same command by changing the last parameter to 2.

diff(x**3+x**2+x,x,2)

The result is the second derivative of the function.

ans = (syms)

2⋅(3⋅x + 1)

Now calculate the **third derivative**

Type the same command again by changing the last parameter to 3

diff(x**3+x**2+x,x,3)

The result is the third derivative of the function.

ans = (syms)

6

You can also derive **functions with two or more variables** f(x, y).

For example, define the symbol of two variables

syms x y

Calculates the first derivative of the function x^{2}y^{2} respect to x

diff(x**2*y**2,x,1)

The result is the **partial derivative** 2xy^{2}.

ans = (syms)

2xy**2

If this short guide by Nigiara on GNU Octave helped you keep following us.