The present invention includes a method for operating a data processing system to compute an approximation to a scalar product between first and second vectors in which each vector is characterized by N components. The method includes replacing the first vector by a third vector that is a pyramid integer vector characterized by N components and an integer K equal to the sum of the absolute values of the N components, and computing a scalar product of the third vector with the second vector to provide the approximation to the scalar product between the first and second vectors. Computing the scalar product of the second and third vectors can be carried out by K additions followed by one floating point multiply.