1. A method for coding an input vector of a present frame using LSP prediction coding, the method comprising the acts of: accumulating codevectors for frames previous to the present frame to produce accumulated codevectors, each codevector being produced by quantizing the difference between a prediction vector and an input vector of a respective frame; accumulating output vectors for frames previous to the present frame to produce accumulated output vectors, each output vector being produced by adding the prediction vector and the codevector of a respective frame; calculating a prediction coefficient matrix for the present frame from the accumulated codevectors and the accumulated output vectors; calculating the prediction vector for the present frame from the accumulated codevectors and from the prediction coefficient matrix of the present frame, the prediction vector being used to predict the input vector of the present frame; calculating the codevector of the present frame by quantizing the difference between the prediction vector and the input vector of the present frame; and calculating an output vector of the present frame by adding together the prediction vector and the codevector of the present frame.