# SVM options in scikit-learn

Just curious about two options in the scikits SVM class.

Does anyone know what scale_C and shrinking do? Not much in the documentation unfortunately.

scale_C=True means that the C parameter of the SVM problem is scaled with the number of samples. This is the default in libSVM and liblinear, however if you train models with a widely-varying number of samples it means that a single value of C will not be adequate for all the models. For this reason, we advocate using scale_C=False. It is documented in the list of parameters of the SVM objects.