PRINT
PRINT "２重音の波形（ 短調編 ）:"
PRINT "ra  si  do  re  mi  fa  so  raa"
PRINT
INPUT PROMPT "第１の音？ ( ra, si, do, ・・・ ） ":AA$
INPUT PROMPT "第２の音？ ( ra, si, do, ・・・ ） ":BB$
PRINT
IF AA$="ra" THEN LET a=40
IF AA$="si" THEN LET a=45
IF AA$="do" THEN LET a=48
IF AA$="re" THEN LET a=53.333
IF AA$="mi" THEN LET a=60
IF AA$="fa" THEN LET a=64
IF AA$="so" THEN LET a=72
IF AA$="raa" THEN LET a=80

IF BB$="ra" THEN LET b=40
IF BB$="si" THEN LET b=45
IF BB$="do" THEN LET b=48
IF BB$="re" THEN LET b=53.333
IF BB$="mi" THEN LET b=60
IF BB$="fa" THEN LET b=64
IF BB$="so" THEN LET b=72
IF BB$="raa" THEN LET b=80
SET WINDOW -1,1,-1,1
FOR y=-1 TO 1 STEP 0.0001
   PLOT LINES: y,SIN(a*y)/4;
   PLOT LINES
NEXT y
SET LINE COLOR 0
FOR yy=-1 TO 1 STEP 0.0001
   PLOT LINES: yy,SIN(a*yy)/4;
   PLOT LINES
NEXT yy
SET LINE COLOR 2
FOR z=-1 TO 1 STEP 0.0001
   PLOT LINES: z,SIN(b*z)/4;
   PLOT LINES
NEXT z
SET LINE COLOR 0
FOR zz=-1 TO 1 STEP 0.0001
   PLOT LINES: zz,SIN(b*zz)/4;
   PLOT LINES
NEXT zz
SET LINE COLOR 4
FOR x=-1 TO 1 STEP 0.0001
   PLOT LINES: x,SIN(a*x)/4+SIN(b*x)/4;
   PLOT LINES
NEXT x
PRINT "ra si do　  re　  mi　fa  so　raa"
PRINT "40 45 48  53.333  60  64  72  80"
PRINT
IF a=53.333 OR b=53.333 THEN GOTO 10
LET c=GCD(a,b)
PRINT "２つの音の振動数の比は ";a/c;"：";b/c;" です。"
10 PRINT
END

EXTERNAL FUNCTION GCD(s,t)      ! 最大公約数を求める関数
   DO
      LET m=MOD(s,t)
      IF m=0 THEN EXIT DO
      LET s=t
      LET t=m
   LOOP
   LET gcd=t
END FUNCTION