Trying to use Mpir.NET with F# on linux

Question

I want to use Mpir.NET with F# (4.5) on Ubuntu 18.04, using dotnet on the command line. Not successful. If there is an easier way to use Mpir.NET on F# linux, please advise.

Followed dotnet instructions at https://learn.microsoft.com/en-us/dotnet/fsharp/get-started/get-started-command-line. The example project using the Newtonsoft.Json package worked fine When I build a project to test Mpir.NET, I get an error as described below.

dotnet new sln -o MpirProj
dotnet new console -lang F# -o src/App

replaced src/App/Program.fs with program from Mpir.NET documentation:

open Mpir.NET

let a = 756749075976907490175905790287846502134Z
let b = 529134916478965674697197076070175107505Z
let c = a*b 
printfn "%O" c

 dotnet add src/App/App.fsproj package Mpir.NET

I get the following info/warn message:

warn : Package 'Mpir.NET 0.4.0' was restored using '.NETFramework,Version=v4.6.1' instead of the project target framework '.NETCoreApp,Version=v2.1'. This package may not be fully compatible with your project. info : Package 'Mpir.NET' is compatible with all the specified frameworks in project 'src/App/App.fsproj'. info : PackageReference for package 'Mpir.NET' version '0.4.0' added to file '/home/doug/f#favs/MpirProj/src/App/App.fsproj'.

dotnet sln add src/App/App.fsproj

the resulting App.fsproj file is :

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp2.1</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <Compile Include="Program.fs" />
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="Mpir.NET" Version="0.4.0" />
  </ItemGroup>

</Project>

do the build

dotnet build

messages

/home/doug/f#favs/MpirProj/src/App/App.fsproj : warning NU1701: Package 'Mpir.NET 0.4.0' was restored using '.NETFramework,Version=v4.6.1' instead of the project target framework '.NETCoreApp,Version=v2.1'. This package may not be fully compatible with your project. App -> /home/doug/f#favs/MpirProj/src/App/bin/Debug/netcoreapp2.1/App.dll

Build succeeded.

When I run, see error messages below

~/f#favs/MpirProj/src/App$ dotnet run

messages

/home/doug/f#favs/MpirProj/src/App/App.fsproj : warning NU1701: Package 'Mpir.NET 0.4.0' was restored using '.NETFramework,Version=v4.6.1' instead of the project target framework '.NETCoreApp,Version=v2.1'. This package may not be fully compatible with your project. /home/doug/f#favs/MpirProj/src/App/App.fsproj : warning NU1701: Package 'Mpir.NET 0.4.0' was restored using '.NETFramework,Version=v4.6.1' instead of the project target framework '.NETCoreApp,Version=v2.1'. This package may not be fully compatible with your project.

Unhandled Exception: System.TypeInitializationException: The type initializer for 'Mpir.NET.mpir' threw an exception. ---> System.Exception: MPIR: can't determine path to the xmpir.so at Mpir.NET.mpir.LocateLibrary(String name) at Mpir.NET.mpir.GetXMPIRLibraryPath() at Mpir.NET.mpir.initialize_hxmpir() at Mpir.NET.mpir..cctor() --- End of inner exception stack trace --- at Mpir.NET.mpir.mpz_init_set_str(String str, UInt32 _base) at Mpir.NET.NumericLiteralZ.FromString(String s) at .$Program.main@() in /home/doug/f#favs/MpirProj/src/App/Program.fs:line 3

Answer 1

You are seeing this issue because the package is for .NET Framework, but you're building and running on .NET Core on Ubuntu. Referencing .NET Framework .dlls for compatibility only works on Windows (if it works elsewhere that's basically just coincidental).

I recommend requesting that the package be updated to support .NET Core, or finding a .NET Core-compatible alternative.

Answer 2

I tried Mpir.NET on windows 10, and the execution time was much slower than using F# bigintegers.
I like many things about F#, but the bigintegers are just slow, and there does not appear to be an alternative.

The best time I got on a Pollard rho factorization problem with F# was 28 seconds. Using the exact same algorithm on Ocaml (Windows 10, Ubuntu, and Fedora), the elapsed time was 10 seconds on all of them.