# Anonymous function as argument
**URL:** https://discourse.julialang.org/t/anonymous-function-as-argument/63473
**Category:** New to Julia
**Created:** [June 24, 2021, 12:11am UTC](https://discourse.julialang.org/t/anonymous-function-as-argument/63473 "2021-06-24T00:11:03Z")
**Posts on this page:** 13
**Page:** 1
### Author:  [@Erasmo98](https://discourse.julialang.org/u/Erasmo98)
#### Post date: [June 24, 2021, 12:11am UTC](https://discourse.julialang.org/t/anonymous-function-as-argument/63473/1 "2021-06-24T00:11:03Z")
Why is common practice to use anonymous funtions where a normal function could be used instead? I’m specilly thinking when using it as an argument of another function. For example:
```julia
plot(0:0.1:2π, x -> sin(x))
```
I’ve seen code like that a lot but I don’t know why since
```julia
plot(0:0.1:2π, sin)
```
works perfectly fine.
---
### Author:  [@jzr](https://discourse.julialang.org/u/jzr)
#### Post date: [June 24, 2021, 12:28am UTC](https://discourse.julialang.org/t/anonymous-function-as-argument/63473/2 "2021-06-24T00:28:01Z")
I haven’t seen that. Can you link to an example?
---
### Author:  [@Erasmo98](https://discourse.julialang.org/u/Erasmo98)
#### Post date: [June 24, 2021, 12:50am UTC](https://discourse.julialang.org/t/anonymous-function-as-argument/63473/3 "2021-06-24T00:50:36Z")
Basically is the same as my MWE but here is [this example from a Chaos course](https://github.com/lbenet/2021-2_TSelecFisComp-1/blob/main/clases/21-Mapeos.jl):
```julia
function analisis_grafico(f, x0::Float64, n::Int, domx=0.0:1/128:1.0)
#Graficamos x->F(x) y x->x
Plt1 = plot(domx, x->f(x),
xaxis=("x", (domx[1], domx[end])),
yaxis=("f(x)"),
color=:blue, legend=false, grid=false)
plot!(Plt1,
domx, identity, color=:blue, linestyle=:dash)
#Se grafican los iterados
analisis_grafico!(Plt1, f, x0, n, domx)
return Plt1
end
```
I’ve seen this in other contexts but I don’t remember them right now.
---
### Author:  [@jzr](https://discourse.julialang.org/u/jzr)
#### Post date: [June 24, 2021, 12:51am UTC](https://discourse.julialang.org/t/anonymous-function-as-argument/63473/4 "2021-06-24T00:51:26Z")
I’d guess they just weren’t thinking about it.
---
### Author:  [@rdeits](https://discourse.julialang.org/u/rdeits)
#### Post date: [June 24, 2021, 1:10am UTC](https://discourse.julialang.org/t/anonymous-function-as-argument/63473/5 "2021-06-24T01:10:46Z")
Yeah, there’s no particular reason to do that, and it’s certainly not necessary. I’d guess that you might occasionally see it in a context where someone is trying to show more generally how an anonymous function /could/ be used, and they’ve just unintentionally chosen an example that could also be written without one.
---
### Author:  [@lmiq](https://discourse.julialang.org/u/lmiq)
#### Post date: [June 24, 2021, 1:29am UTC](https://discourse.julialang.org/t/anonymous-function-as-argument/63473/6 "2021-06-24T01:29:59Z")
In that particular case that is not needed, but if they wanted to use an additional parameter for the function they could have done something like:
```julia
f(x,a) = a*x
function analisis_grafico(f, x0::Float64, n::Int, domx=0.0:1/128:1.0)
a = 5.0
Plt1 = plot(domx, x->f(x,a),
...
```
because the `plot` function is expecting a function with one variable, but you want to pass to it a function with two, one being a fixed parameter.
---
### Author:  [@amrods](https://discourse.julialang.org/u/amrods)
#### Post date: [June 24, 2021, 1:35am UTC](https://discourse.julialang.org/t/anonymous-function-as-argument/63473/7 "2021-06-24T01:35:14Z")
I have used something similar when the function `f` takes keyword arguments that I want to move away from the default values.
---
### Author:  [@Erasmo98](https://discourse.julialang.org/u/Erasmo98)
#### Post date: [June 24, 2021, 2:51am UTC](https://discourse.julialang.org/t/anonymous-function-as-argument/63473/8 "2021-06-24T02:51:11Z")
🤔
---
### Author:  [@Erasmo98](https://discourse.julialang.org/u/Erasmo98)
#### Post date: [June 24, 2021, 2:56am UTC](https://discourse.julialang.org/t/anonymous-function-as-argument/63473/9 "2021-06-24T02:56:05Z")
Yeah, I was also thinking that it would be necesary in the following example:
```julia
plot(0:0.1:2π, x -> sin(x^2))
```
---
### Author:  [@Erasmo98](https://discourse.julialang.org/u/Erasmo98)
#### Post date: [June 24, 2021, 2:57am UTC](https://discourse.julialang.org/t/anonymous-function-as-argument/63473/10 "2021-06-24T02:57:08Z")
Do you have an example?
---
### Author:  [@amrods](https://discourse.julialang.org/u/amrods)
#### Post date: [June 24, 2021, 3:08am UTC](https://discourse.julialang.org/t/anonymous-function-as-argument/63473/11 "2021-06-24T03:08:01Z")
```julia
function f(x; exponent=2)
sin(x^exponent)
end
plot(0:0.1:2π, x -> f(x; exponent=3))
```
---
### Author:  [@Erasmo98](https://discourse.julialang.org/u/Erasmo98)
#### Post date: [June 25, 2021, 5:24pm UTC](https://discourse.julialang.org/t/anonymous-function-as-argument/63473/12 "2021-06-25T17:24:03Z")
Got it, thanks. (:
---
### Author:  [@Erasmo98](https://discourse.julialang.org/u/Erasmo98)
#### Post date: [June 25, 2021, 5:30pm UTC](https://discourse.julialang.org/t/anonymous-function-as-argument/63473/13 "2021-06-25T17:30:41Z")
Thank you all for your replies. In the example I gave, there is no need to use an anonymous function but it is necessary to reduce the number of arguments of a function.