1. A convolution accelerator, comprising: a transformation crossbar array programmed to calculate a Fourier Transformation of a first vector with a transformation matrix and a Fourier Transformation of a second vector with the transformation matrix; a circuit to multiply the Fourier Transformation of the first vector with the Fourier Transformation of the second vector to calculate a product vector; and an inverse transformation crossbar array programmed to calculate an Inverse Fourier Transformation of the product vector according to an inverse transformation matrix.