The a terms are referred to as ATR

The a terms are referred to as ATR (Arc Tangent 5) Radix)constants, and are precompute and stored in r. the computer. The terms are referred to as ATRd digits and are determined during each operation. In the CORDIC computer, the ATR digits are de- t termined sequentially, most significant digit first, andn are used to control the conditional action of the adder- subtractors in the arithmetic unit. The following para- graphs contain a description of the manner in which the ATR code representation, 15253.. En, can be deter- mined for any given angle, or 6. First, for any angle,or, there must be at least one set of values for the operators that will satisfy(20)or (21). Second, a simple technique must be available for determining the ATR code digits that satisfy these equations. The following relationships are necessary and suf- ficient for any sequence of radix constants to meet the above requirements.