# Seven Lines of Julia (examples sought)

**URL:** <https://discourse.julialang.org/t/seven-lines-of-julia-examples-sought/50416>\
**Category:** General Usage\
**Created:** [November 19, 2020, 7:37am UTC](https://discourse.julialang.org/t/seven-lines-of-julia-examples-sought/50416 "2020-11-19T07:37:29Z")\
**Posts on this page:** 1\
**Showing post:** 42

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**Author:** ![lmiq](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/lmiq/32/18314_2.png) [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Post date:** [November 24, 2020, 1:14pm UTC](https://discourse.julialang.org/t/seven-lines-of-julia-examples-sought/50416/42 "2020-11-24T13:14:26Z")

</div>

With 15 lines I could write a code to perform a particle simulation with periodic boundary conditions, a langevin thermostat, and a quadratic potential between the particles, and produce an animation:

```julia
using Plots ; ENV["GKSwstype"]="nul"
const N, τ, Δt, λ, T, k = 100, 1000, 0.01, 1e-3, 0.26, 1e-6
const x, v, f = -0.5 .+ rand(3,N), -0.01 .+ 0.02*randn(3,N), zeros(3,N)
wrap(x,y) = (x-y) > 0.5 ? (x-y)-1 : ( (x-y) < -0.5 ? (x-y)+1 : (x-y) )
anim = @animate for t in 1:τ 
  f .= 0
  for i in 1:N-1, j in i+1:N 
    f[:,i] .+= wrap.(x[:,i],x[:,j]) .- λ .* v[:,i]
    f[:,j] .+= wrap.(x[:,j],x[:,i]) .- λ .* v[:,j]
  end 
  x .= wrap.(x .+ v*Δt .+ (f/2)*Δt^2,zeros(3))
  v .= v .+ f*Δt .+ sqrt.(2*λ*k*T*Δt)*randn()
  scatter(x[1,:],x[2,:],x[3,:],label="",lims=(-0.5,0.5),aspect_ratio=1,framestyle=:box)
end
gif(anim,"anim.gif",fps=10)

```

![anim](https://global.discourse-cdn.com/julialang/original/3X/4/d/4d3bbfefe4d023a48653553c5fa187cb2821a228.gif)

As Tamas mentioned, if we go to a few more lines, this could include an actual Lennard-Jones potential and be parallelized. And that without using any package besides Plots.

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