PRINT
PRINT "２重音の波形（ 長調編 ）:"
PRINT "do  re  mi  fa  so  ra  si  doo"
PRINT
INPUT PROMPT "第１の音？ ( do, re, mi, ・・・ ） ":AA$
INPUT PROMPT "第２の音？ ( do, re, mi, ・・・ ） ":BB$
PRINT
IF AA$="do" THEN LET a=24
IF AA$="re" THEN LET a=27
IF AA$="mi" THEN LET a=30
IF AA$="fa" THEN LET a=32
IF AA$="so" THEN LET a=36
IF AA$="ra" THEN LET a=40
IF AA$="si" THEN LET a=45
IF AA$="doo" THEN LET a=48
IF BB$="do" THEN LET b=24
IF BB$="re" THEN LET b=27
IF BB$="mi" THEN LET b=30
IF BB$="fa" THEN LET b=32
IF BB$="so" THEN LET b=36
IF BB$="ra" THEN LET b=40
IF BB$="si" THEN LET b=45
IF BB$="doo" THEN LET b=48
SET WINDOW -2,2,-2,2
FOR y=-2 TO 2 STEP 0.0001
   PLOT LINES: y,SIN(a*y)/4;
   PLOT LINES
NEXT y
SET LINE COLOR 0
FOR yy=-2 TO 2 STEP 0.0001
   PLOT LINES: yy,SIN(a*yy)/4;
   PLOT LINES
NEXT yy
SET LINE COLOR 2
FOR z=-2 TO 2 STEP 0.0001
   PLOT LINES: z,SIN(b*z)/4;
   PLOT LINES
NEXT z
SET LINE COLOR 0
FOR zz=-2 TO 2 STEP 0.0001
   PLOT LINES: zz,SIN(b*zz)/4;
   PLOT LINES
NEXT zz
SET LINE COLOR 4
FOR x=-2 TO 2 STEP 0.0001
   PLOT LINES: x,SIN(a*x)/4+SIN(b*x)/4;
   PLOT LINES
NEXT x
PRINT "do  re  mi  fa  so  ra  si  doo"
PRINT "24  27  30  32  36  40  45  48"
PRINT
LET c=GCD(a,b)
PRINT "２つの音の振動数の比は ";a/c;"：";b/c;" です。"
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