Accord.NET Framework is described as 'The Accord.NET Framework is a .NET machine learning framework combined with audio and image processing libraries completely written in C#'. There are five alternatives to Accord.NET Framework for a variety of platforms, including Windows, Linux, Mac, BSD and ASP.NET. The best alternative is GNU Octave, which is both free and Open Source. Other great apps like Accord.NET Framework are R (programming language) (Free, Open Source), OpenCV (Free, Open Source), VideoUltimate (Paid) and LeptonicaSharp (Free, Open Source).
Octave is a computer program for performing numerical computations which is mostly compatible with MATLAB. It is part of the GNU Project. It is free software under the terms of the GNU General Public License.