# Functions

### Overview

You can use function notation as an easy, efficient way of using equations without re-writing them. For example, you can evaluate a function at a certain point:

You can use the notation f(x,y), for example, to define a function with more than one variable:

Defining a function once allows you to use this function within other functions.

Or, you can combine multiple functions together to create a separate function.

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• skylord a52

Are there any plans to eventually implement recursive functions?

• Caleb Parks

Functions should be able to accept points as arguments. It would be very helpful.

• Pegasusroe

Actually, Desmos can define many-to-many functions, but I can't find it documented anywhere on the official site here. For example, you can define a determinant function like this:

d(U,V)=U[1]V[2] - U[2]V[1]

then:

d([1,2], [3,4]) will be 4 - 6 = -2

You can even define a cross product function in 3D space like this:

c(U,V) = [ d([U[2], U[3]], [V[2], V[3]]), d([U[3], U[1]], [V[3], V[1]]), d([U[1], U[2]], [V[1], V[2]]) ]

I know it's complicated, but it works like a charm!

Edited by Pegasusroe
• Philippe BAUCOUR

Bonjour,

Very quick. Can we define function names with more than one letters like :

TempEngine (t) = ....

Derivative (t) =

Numerator (x) =....

Denom(x) = ....

Ratio(x) = Numerator(x)/Denom(x)

The help file should at least explain what is possible and what is not.We (the users) would save lot of time. Best regards, Philippe

• Dmitry Kudriavtsev

Is there a way to have a function return a function?

• Leslie Koller

Your f(x,y) never uses the y variable...it is essentially a one-variable function.  I was looking for how to graph f(x,y)=x+y+xy?