In this paper, we present the first analysis of the accuracy of both addition and multiplication on a multichannel optical matrix processor. We performed our analysis on an analog optical vector-matrix processor capable of performing 120 M operations per second with an 8-element input vector, 8 x 8 matrix and 8-element output. We examine the accuracy with which numbers are represented for both the acoustooptic vector input and the liquid crystal matrix input, the accuracy of multiplication on a single channel, the accuracy of addition on two channels as well as the accuracy of multiplication and addition on two channels. From this analysis, we can conclude that while vector input numbers are represented with 7.7 bit accuracy, the results of two-channel multiplication and addition are only accurate to within 1 .3 % or 6.3 bits.