DMRG code example error

ITensor Julia Questions
1

Hi, I am working on Julia 1.8.2 and trying to run the code example on the webpage DMRG Examples · ITensors.jl

using ITensors

let
  N = 100
  sites = siteinds("S=1",N)

  os = OpSum()
  for j=1:N-1
    os += 0.5,"S+",j,"S-",j+1
    os += 0.5,"S-",j,"S+",j+1
    os += "Sz",j,"Sz",j+1
  end
  H = MPO(os,sites)

  nsweeps = 5 # number of sweeps is 5
  maxdim = [10,20,100,100,200] # gradually increase states kept
  cutoff = [1E-10] # desired truncation error

  psi0 = randomMPS(sites,2)

  energy,psi = dmrg(H,psi0; nsweeps, maxdim, cutoff)

  return
end

But it gives an error saying that

ERROR: MethodError: no method matching sort(::Tuple{Index{Int64}, Index{Int64}}; by::typeof(plev))

And the Stacktrace is

Stacktrace:
 [1] permute(M::MPO, #unused#::Tuple{typeof(linkind), typeof(siteinds), typeof(linkind)})
   @ ITensors F:\Julia-1.8.2\packages\packages\ITensors\hLDmL\src\mps\dmrg.jl:13
 [2] #dmrg#1051
   @ F:\Julia-1.8.2\packages\packages\ITensors\hLDmL\src\mps\dmrg.jl:25 [inlined]
 [3] dmrg
   @ F:\Julia-1.8.2\packages\packages\ITensors\hLDmL\src\mps\dmrg.jl:20 [inlined]
 [4] #dmrg#1057
   @ F:\Julia-1.8.2\packages\packages\ITensors\hLDmL\src\mps\dmrg.jl:375 [inlined]
 [5] top-level scope
   @ .\Untitled-1:21

I succeeded in running this piece of code previously but it doesn’t work today. Updating Julia to latest version doesn’t help. How may I solve this problem?

Thanks!

2

That looks like an error that occurred in an older version of ITensors.jl. Could you try updating all of your packages and also share the output of using Pkg; Pkg.status()?

3

Below is updating all the packages and the output of Pkg.status():

(entanglement_code) pkg> update
┌ Warning: attempting to remove probably stale pidfile
│   path = "F:\\Julia-1.8.2\\packages\\registries\\.pid"
└ @ FileWatching.Pidfile F:\Julia-1.9.2\share\julia\stdlib\v1.9\FileWatching\src\pidfile.jl:244
    Updating registry at `F:\Julia-1.8.2\packages\registries\General`
    Updating git-repo `https://github.com/JuliaRegistries/General.git`
  No Changes to `D:\entanglement_code\Project.toml`
  No Changes to `D:\entanglement_code\Manifest.toml`

julia> using Pkg

julia> Pkg.status()
Status `D:\entanglement_code\Project.toml`
  [336ed68f] CSV v0.10.14   
  [5a033b19] CurveFit v0.6.0
  [28b8d3ca] GR v0.73.3     
  [d2c73de3] GR_jll v0.73.3+0
4

Maybe I’m missing something but I don’t see ITensors listed there. Also it seems like there is something wrong with your package registry, maybe you should try removing the registry (7. Registries · Pkg.jl) and then reinstall your packages.

2 Likes
5

It works now! Thanks!