A direct coupled function generator has been developed which provides a fourth degree polynomial function in times of the order of 100 nsec. Analog multipliers utilizing field effect transistors are used. A unique circuit configuration allows the generation of a fourth degree polynomial having individually adjustable coefficients with only two multipliers. The instrument, operating at 5 V input and output levels, achieves an accuracy of 1% for the lower order terms and 2% for the higher order terms.