1. A method for encoding symbols in a symbol stream to compress the amount of data required to represent a signal corresponding to the symbol stream, the method comprising: obtaining a current symbol in the symbol stream; and encoding the current symbol, such encoding being the result of: using a modeling function to determine, for symbol values local to the current symbol, a modeling value based upon the magnitudes of such symbol values; and using the modeling value to determine a probability function that associates a probability value with each of the symbols in the stream; and using the probability function in encoding the current symbol.