<> <> <> <> DIRECTORY Real, RealFns, SVAngle; SVAngleImpl: PROGRAM IMPORTS Real, RealFns EXPORTS SVAngle = BEGIN Normalize: PUBLIC PROC [anyRange: REAL] RETURNS [range180: REAL] = { <> IF anyRange > 180 THEN { <> realNumberOf360s: REAL _ anyRange/360; fixNumberOf360s: NAT _ Real.FixC[realNumberOf360s];-- FixC truncates numberToSubtract: REAL _ fixNumberOf360s*360.0; RETURN[anyRange-numberToSubtract]; }; IF anyRange <= -180 THEN { <> realNumberOf360s: REAL _ -anyRange/360; fixNumberOf360s: NAT _ Real.FixC[realNumberOf360s];-- FixC truncates numberToAdd: REAL _ (fixNumberOf360s + 1)*360.0; RETURN[anyRange+numberToAdd]; }; range180 _ anyRange }; -- end of Normalize Add: PUBLIC PROC [position, increment: REAL] RETURNS [finalPosition: REAL] = { <> finalPosition _ position + increment; -- -540 < finalPosition < 540 IF finalPosition > 180 THEN finalPosition _ finalPosition - 360 ELSE IF finalPosition <= -180 THEN finalPosition _ finalPosition + 360; }; -- end of Add ClockwiseAngle: PUBLIC PROC [fromPosition, toPostion: REAL] RETURNS [increment: REAL] = { <> increment _ 0; IF fromPosition < 0 THEN {-- start in lower semi-circle. <> IF -180 < toPostion AND toPostion <= fromPosition THEN RETURN[toPostion - fromPosition] ELSE increment _ increment + (-180 - fromPosition); IF 0 <= toPostion AND toPostion <= 180 THEN RETURN[increment + (toPostion-180)] ELSE increment _ increment + 180; RETURN[increment + toPostion]; } ELSE { -- start in upper semi-circle. <> IF fromPosition < toPostion AND toPostion <= 180 THEN RETURN [toPostion - fromPosition - 360] ELSE RETURN[toPostion - fromPosition]; }; }; -- end of ClockwiseAngle CounterClockwiseAngle: PUBLIC PROC [fromPosition, toPostion: REAL] RETURNS [increment: REAL] = { <> <> increment _ 360 + ClockwiseAngle[fromPosition, toPostion]; IF increment = 360 THEN increment _ 0; }; ShortestDifference: PUBLIC PROC [position1, position2: REAL] RETURNS [pos1MinusPos2: REAL] = { <> clockwise: REAL _ ClockwiseAngle[position1, position2]; pos1MinusPos2 _ IF clockwise <= -180 THEN clockwise + 360 ELSE clockwise; }; Scale: PUBLIC PROC [angle: REAL, scalar: REAL] RETURNS [angleTimesScalar: REAL] = { <> angleTimesScalar _ angle*scalar; angleTimesScalar _ Normalize[angleTimesScalar]; }; ArcTan: PUBLIC PROC [numerator, denominator: REAL] RETURNS [degrees: REAL] = { <> degrees _ RealFns.ArcTanDeg[numerator, denominator]; degrees _ Normalize[degrees]; -- Normalize may not be needed. RealFns seems to do the right thing }; END.