| 摘要 |
PURPOSE: To provide a method for calculating a reciprocal of a square root with which a higher speed operation than that of a square root reciprocal arithmetic circuit using the conventional divider and square root extractor can be carried out and hardwares can be saved. CONSTITUTION: The method for calculating the reciprocal of a square root when a radix is r supposing that an intermediate result after j times repeated calculation is S£j|, a balance is W£j|, and the product of an operand X and the intermediate result S£j| is P£j| comprises a step for setting proper values for initial values S£0|, W£0|, and P£0| and a step for selecting a digit qj+1 of the reciprocal of a square root from a digit set {-a,..., -1, 0, 1,..., a} by a digital selecting circuit, and for performing n times repeated arithmetic operation from j=0 to (n-1) concerning a recurrence formula related with the intermediate result S£j|; S£j+1|:=S£j|+qj+1r¬-j-1, a recurrence formula related with the balance W£j|; W£j+1|:=rW£j|-(2P£j|+Xqj+1r¬-j-1)qj+1, and a recurrence formula related with the product P£j|; P£j+1|:=P£j|+Xqj+1r¬-j-1 by using one digit multiplier, adder, and converter.
|
