# Unable to make multiple lines in Plots
**URL:** https://discourse.julialang.org/t/unable-to-make-multiple-lines-in-plots/49401
**Category:** General Usage
**Tags:** plotting
**Created:** [November 1, 2020, 7:17am UTC](https://discourse.julialang.org/t/unable-to-make-multiple-lines-in-plots/49401 "2020-11-01T07:17:11Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)
#### Post date: [November 1, 2020, 7:17am UTC](https://discourse.julialang.org/t/unable-to-make-multiple-lines-in-plots/49401/1 "2020-11-01T07:17:11Z")
I tried to plot 2 lines on the same graph
```julia
using Plots
f(x)=x^2
d(x)=2x
plot(f)
plot!(d)
```
But when I try to run this I get an error.
```julia
ERROR: UndefVarError: plot! not defined
Stacktrace:
[1] top-level scope at REPL[673]:1
```
Do I have all the right packeges? Do I have the right syntax? including comas and semicolons?
---
### Author:  [@Ahmed\_Salih](https://discourse.julialang.org/u/Ahmed_Salih)
#### Post date: [November 1, 2020, 7:37am UTC](https://discourse.julialang.org/t/unable-to-make-multiple-lines-in-plots/49401/2 "2020-11-01T07:37:18Z")
> [@brett\_knoss](#):
>
> ```julia
> using Plots
>
> f(x)=x^2
> d(x)=2x
>
> plot(f)
> plot!(d)
>
> ```
Using Julia 1.5.0 the code works fine:
Perhaps try `] update`. The “]” is important it lets you enter “pkg” mode. Then backspace to leave it afterwards. If it still does not work, try:
```julia
using Pkg
Pkg.rm("Plots")
Pkg.add("Plots")
```
Kind regards
---
### Author:  [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)
#### Post date: [November 1, 2020, 5:53pm UTC](https://discourse.julialang.org/t/unable-to-make-multiple-lines-in-plots/49401/3 "2020-11-01T17:53:45Z")
I might try that. A thing came up on VS Code, saying indexing packages, and now I can’t seem to add new packages, or start. packages. I can’t do one plot now. I just get an error.
```julia
julia> plot(f)
ERROR: error compiling _plot!: error compiling _display: could not load library "libGR.dll"
The specified module could not be found.
Stacktrace:
[1] #plot#131(::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}, ::typeof(plot), ::Function) at C:\Users\Brett\.julia\packages\Plots\uCh2y\src\plot.jl:57
[2] plot(::Function) at C:\Users\Brett\.julia\packages\Plots\uCh2y\src\plot.jl:51
[3] top-level scope at REPL[3]:100:
```
---
### Author:  [@Ahmed\_Salih](https://discourse.julialang.org/u/Ahmed_Salih)
#### Post date: [November 1, 2020, 5:56pm UTC](https://discourse.julialang.org/t/unable-to-make-multiple-lines-in-plots/49401/4 "2020-11-01T17:56:27Z")
You have to build GR, try:
```julia
using Pkg
Pkg.build("Plots")
Pkg.build("GR")
```
Kind regards
---
### Author:  [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)
#### Post date: [November 1, 2020, 6:55pm UTC](https://discourse.julialang.org/t/unable-to-make-multiple-lines-in-plots/49401/5 "2020-11-01T18:55:45Z")
Awesome! It all seems to work now. Now how do I add a horizontal line?
when I add:
```julia
hline!(1)
```
I get :
```julia
hline!(1)
ERROR: BoundsError: attempt to access 0-element Array{Float64,1} at index [1]
Stacktrace:
[1] getindex(::Array{Float64,1}, ::Int64) at .\array.jl:744
[2] expand_extrema!(::Plots.Subplot{Plots.GRBackend}, ::RecipesPipeline.DefaultsDict) at C:\Users\Brett\.julia\packages\Plots\uCh2y\src\axes.jl:350
[3] _expand_subplot_extrema(::Plots.Subplot{Plots.GRBackend}, ::RecipesPipeline.DefaultsDict, ::Symbol) at C:\Users\Brett\.julia\packages\Plots\uCh2y\src\pipeline.jl:361
[4] add_series!(::Plots.Plot{Plots.GRBackend}, ::RecipesPipeline.DefaultsDict) at C:\Users\Brett\.julia\packages\Plots\uCh2y\src\pipeline.jl:312
[5] _process_seriesrecipe(::Plots.Plot{Plots.GRBackend}, ::RecipesPipeline.DefaultsDict) at C:\Users\Brett\.julia\packages\RecipesPipeline\tkFmN\src\series_recipe.jl:44
[6] _process_seriesrecipe(::Plots.Plot{Plots.GRBackend}, ::RecipesPipeline.DefaultsDict) at C:\Users\Brett\.julia\packages\RecipesPipeline\tkFmN\src\series_recipe.jl:58
[7] _process_seriesrecipes!(::Plots.Plot{Plots.GRBackend}, ::Array{Dict{Symbol,Any},1})
at C:\Users\Brett\.julia\packages\RecipesPipeline\tkFmN\src\series_recipe.jl:25
[8] recipe_pipeline!(::Plots.Plot{Plots.GRBackend}, ::Dict{Symbol,Any}, ::Tuple{Int64})
at C:\Users\Brett\.julia\packages\RecipesPipeline\tkFmN\src\RecipesPipeline.jl:96
[9] _plot!(::Plots.Plot{Plots.GRBackend}, ::Dict{Symbol,Any}, ::Tuple{Int64}) at C:\Users\Brett\.julia\packages\Plots\uCh2y\src\plot.jl:167
[10] #plot!#136(::Base.Iterators.Pairs{Symbol,Symbol,Tuple{Symbol},NamedTuple{(:seriestype,),Tuple{Symbol}}}, ::typeof(plot!), ::Plots.Plot{Plots.GRBackend}, ::Int64) at C:\Users\Brett\.julia\packages\Plots\uCh2y\src\plot.jl:158
[11] (::RecipesBase.var"#kw##plot!")(::NamedTuple{(:seriestype,),Tuple{Symbol}}, ::typeof(plot!), ::Plots.Plot{Plots.GRBackend}, ::Int64) at .\none:0
[12] #plot!#135(::Base.Iterators.Pairs{Symbol,Symbol,Tuple{Symbol},NamedTuple{(:seriestype,),Tuple{Symbol}}}, ::typeof(plot!), ::Int64) at C:\Users\Brett\.julia\packages\Plots\uCh2y\src\plot.jl:150
[13] (::RecipesBase.var"#kw##plot!")(::NamedTuple{(:seriestype,),Tuple{Symbol}}, ::typeof(plot!), ::Int64) at .\none:0
[14] #hline!#378 at C:\Users\Brett\.julia\packages\RecipesBase\aQmWx\src\RecipesBase.jl:403 [inlined]
[15] hline!(::Int64) at C:\Users\Brett\.julia\packages\RecipesBase\aQmWx\src\RecipesBase.jl:403
[16] top-level scope at REPL[14]:1
```
---
### Author:  [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)
#### Post date: [November 1, 2020, 7:29pm UTC](https://discourse.julialang.org/t/unable-to-make-multiple-lines-in-plots/49401/6 "2020-11-01T19:29:01Z")
try `hline!([1])`
---
### Author:  [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)
#### Post date: [November 1, 2020, 7:36pm UTC](https://discourse.julialang.org/t/unable-to-make-multiple-lines-in-plots/49401/7 "2020-11-01T19:36:52Z")
Yup, lol. I should have found that. I don’t see anything though about changing the spacing of x
```julia
using Plots
f(x)=x^2
plot(1:10,f)
```
I get jagged lines, I’d like to know if i can make the line smoother, or if I need to change the backend to do that.
---
### Author:  [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)
#### Post date: [November 1, 2020, 7:38pm UTC](https://discourse.julialang.org/t/unable-to-make-multiple-lines-in-plots/49401/8 "2020-11-01T19:38:49Z")
just use a more fine-grained `x`, like `plot(range(0, 1, length = 1000), f)`