# The usage of \`QMDP\`

**URL:** <https://discourse.julialang.org/t/the-usage-of-qmdp/41518>\
**Category:** General Usage\
**Created:** [June 16, 2020, 1:25pm UTC](https://discourse.julialang.org/t/the-usage-of-qmdp/41518 "2020-06-16T13:25:01Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![jkwwwwow](https://avatars.discourse-cdn.com/v4/letter/j/ecb155/32.png) [@jkwwwwow](https://discourse.julialang.org/u/jkwwwwow)\
**Post date:** [June 16, 2020, 1:25pm UTC](https://discourse.julialang.org/t/the-usage-of-qmdp/41518/1 "2020-06-16T13:25:01Z")

</div>

Hello everyone, I’m not particularly sure if I posted this content in the appropriate section.  
I am trying to run a program on Github ([https://github.com/mexsser/POMDPIDMModel.jl](https://github.com/mexsser/POMDPIDMModel.jl)), but when I finish the installation part and run the program , I receive the following error:

```julia
  LoadError: MethodError: no method matching QMDP.QMDPSolver(; max_iterations=7, tolerance=0.0001, verbose=true)
  Closest candidates are:
    QMDP.QMDPSolver(; max_iterations, belres, verbose) at /home/jkwwwwow/.julia/packages/QMDP/LiM5S/src/vanilla.jl:24 got unsupported keyword argument "tolerance"
    QMDP.QMDPSolver(!Matched::S) where S<:Union{DiscreteValueIteration.SparseValueIterationSolver, DiscreteValueIteration.ValueIterationSolver} at /home/jkwwwwow/.julia/packages/QMDP/LiM5S/src/vanilla.jl:21 got unsupported keyword arguments "max_iterations", "tolerance", "verbose"
  

```

It seems that there is a problem with this code:

```julia
solver = QMDP.QMDPSolver(max_iterations=7, tolerance=1e-4, verbose=true)

```

Then I checked the [QMDP’s repository](https://github.com/JuliaPOMDP/QMDP.jl#usage) on github and changed the code to:

```julia
solver = QMDP.QMDPSolver(max_iterations=7, belres=1e-4, verbose=true)

```

After that I received this error:

```julia
LoadError: type QMDPSolver has no field max_iterations
  Stacktrace:
   [1] getproperty(::QMDP.QMDPSolver{DiscreteValueIteration.ValueIterationSolver}, ::Symbol) at ./Base.jl:33
   [2] solve(::QMDP.QMDPSolver{DiscreteValueIteration.ValueIterationSolver}, ::DrivePOMDP; sparse::Bool) at /home/jkwwwwow/.julia/packages/POMDPIDMModel/LoQFH/src/QMDPMod.jl:0
   [3] top-level scope at /home/jkwwwwow/POMDPIDMModel.jl-master/test/tests.jl:79
   [4] include(::String) at ./client.jl:439
   [5] top-level scope at /home/jkwwwwow/POMDPIDMModel.jl-master/test/runtests.jl:4
   [6] top-level scope at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.4/Test/src/Test.jl:1113
   [7] top-level scope at /home/jkwwwwow/POMDPIDMModel.jl-master/test/runtests.jl:4
   [8] include(::Module, ::String) at ./Base.jl:377
   [9] exec_options(::Base.JLOptions) at ./client.jl:288
   [10] _start() at ./client.jl:484
  in expression starting at /home/jkwwwwow/POMDPIDMModel.jl-master/test/tests.jl:79

```

What does `QMDPSolver has no field max_iterations` mean?  
Any suggestions on the correct usage of `QMDP.QMDPSolver` ?