I have been looking for a free software with the same functionalities of Matlab Neural Networks toolbox. I have read some documents, mainly on freemat, but up to now nothing promising: any suggestion?
there are some alternatives out there, but depending on what you want exactly, you may choose a different option.
R is quite useful, but the hard standard nowadays is python as Toto Haryanto said above, there you can easily combine libraries such as:
OpenCv, that contains SVM machines, Gaussian mixture models and others, for computer vision and image processing.
sklearn, that contains several tools for data processing and machine learning techniques
Tensorflow, is probably the most popular one, combined with Keras or another API that simplifies its operation is nowadays the most popular deep learning toolbox.
You want to install all the above with tools such as matplotlib, that brings the matlab plot functionality, numpy for a standardized representation of data, and some hdf5 library, I think pytables is one i use, to create standardized datasets in hdf5 format.
Combine those with some other libraries you like, and you have the most powerful free environment for machine learning today.
Frankly, the amount you would spend on buying MATLAB tool box (edu version) is definitely far less than the 'cost' incurred in spending months of time in figuring out these tools.