Calculation of trigonometric functions using four input inner product circuits

摘要

PROBLEM TO BE SOLVED: To provide a circuit that uses a four element dot product circuit (DP4) in order to approximate an argument t=x/pi for an input x, for trigonometric function computation.SOLUTION: An argument is input to a trigonometric function such as Sin Pi( ) or Cos Pi( ). A DP4 circuit calculates a representation of x multiplied by the reciprocal of pi. Bits for the reciprocal of pi used are selected based on the magnitude of the exponent of x. The DP4 circuit includes four multipliers 100a to 100d, two intermediate adders 102a to 102b, and a final adder 106. Outputs of the multipliers, intermediate adders, and final adder are adjusted such that the output of the final adder is a value of the argument t that will provide an accurate output when input to the trigonometric function.SELECTED DRAWING: Figure 1