!Hyperbola

LET Xmax = 5
LET Ymax = 5
SET WINDOW -Xmax,Xmax,-Ymax,Ymax
SET POINT STYLE 1
DRAW AXES 

LET stp = 0.01
LET e = 0.005
LET c = 1 
LET sa = 1.5

FOR x=-Xmax TO Xmax STEP stp
   FOR y=-Ymax TO Ymax STEP stp
      LET r1 = SQR((-x-c)*(-x-c) + y*y)
      LET r2 = SQR((x-c)*(x-c) + y*y)
      LET s = ABS(r1 - r2)
      IF ABS(s - sa) < e THEN
         PLOT POINTS :x, y
      END IF
   NEXT y
NEXT x

END
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!Apollonius

LET Xmax = 5
LET Ymax = 5
SET WINDOW -Xmax,Xmax,-Ymax,Ymax
SET POINT STYLE 1
DRAW AXES 

LET stp = 0.01
LET e = 0.005
LET c =1
LET ratio = 2

FOR x=-Xmax TO Xmax STEP stp
   FOR y=-Ymax TO Ymax STEP stp
      LET r1 = SQR((-x-c)*(-x-c) + y*y)
      LET r2 = SQR((x-c)*(x-c) + y*y)
      IF (ABS(x)<>c)AND(y<>0) THEN
         LET s = r2 / r1
         IF ABS(s - ratio) < e THEN
            PLOT POINTS :x, y
         END IF
      END IF
   NEXT y
NEXT x

END