A method of performing matrix multiplication using optical processing is presented. It combines speed due to the inherent parallelism of optics and high accuracy due to the digital representation of the multiplied numbers. The multiplication of numbers is performed by spatially convolving their binary digital representations. The spatial convolution is realized by frequency-domain multiplication. Real-time recording is necessary. An architecture for vector-vector multiplication is also proposed. The real-time recording is performed by real-time holography using fourwave optical mixing.