OPTION ANGLE DEGREES
SET COLOR mode "NATIVE"
PRINT 
PRINT "到彼岸のイメージ"
PRINT
PRINT "    凡夫 → 菩薩 → 仏"
PRINT
SET WINDOW -2,2,-2,2
SET LINE WIDTH 3
DRAW AXES (10,10)
LET a=1
LET b=1
FOR t=0 TO 360 STEP 0.5
   PLOT LINES: a*COS(t)-0.5,b*SIN(t);
NEXT t
PLOT LINES
SET AREA COLOR colorindex(90/255,90/255,0/255)
PAINT -0.5,0
LET f=SQR(a^2-b^2)-0.5
SET POINT COLOR colorindex(0/255,0/255,0/255)
PLOT POINTS:-f,0;f,0
WAIT DELAY 5
CLEAR
DRAW AXES (10,10)
LET a=SQR(1.25)
LET b=1
SET LINE WIDTH 3
FOR t=0 TO 360 STEP 0.5
   PLOT LINES: a*cos(t),b*sin(t);
NEXT t
PLOT LINES
SET AREA COLOR colorindex(235/255,235/255,50/255)
PAINT 0,0
LET f=SQR(a^2-b^2)
SET POINT COLOR colorindex(0/255,0/255,0/255)
PLOT POINTS:-f,0;f,0
WAIT DELAY 5
CLEAR
LET a=1
LET b=1
SET LINE COLOR colorindex(255/255,255/255,100/255)
FOR i=0 TO 180 STEP 2
   CALL SEN2(0,0,COS(i),SIN(i),-10,10)
   PLOT LINES
NEXT i
PLOT LINES
DRAW AXES (10,10)
SET LINE COLOR colorindex(0/255,0/255,0/255)
SET LINE WIDTH 3
FOR t=0 TO 360 STEP 0.5
   PLOT LINES: a*cos(t),b*sin(t);
NEXT t
PLOT LINES
SET AREA COLOR colorindex(255/255,255/255,100/255)
PAINT 0,0
LET f=SQR(a^2-b^2)
SET POINT COLOR colorindex(0/255,0/255,0/255)
PLOT POINTS:-f,0;f,0
END

EXTERNAL SUB SEN2(a,b,c,d,e,f)     !(a,b),(c,d)を結ぶ直線を描く
SET LINE WIDTH 3
FOR x=e TO f STEP 0.05
   IF a=c THEN
      PLOT LINES:a,-100;a,100
      GOTO 10
   END IF
   LET m=(b-d)/(a-c)
   LET n=b-a*(b-d)/(a-c)
   PLOT LINES: x,m*x+n;
10 NEXT x
END SUB