PROGRAM LSYS_LEVY_CURVE   !(2 versions) © W.van Duyn 24th April 2004
SET MODE "color"
SET WINDOW 0,1199,0,903
SET BACKGROUND COLOR "white"
CLEAR
CALL init
END

SUB init
OPTION ANGLE degrees
PRINT "input: x try 600, y try 450"
INPUT x,y
PRINT "input: Side try 240,level try 10 dimension try 4"
INPUT side,level,ak
CLEAR
SET COLOR "black"
FLOOD 1,1
LET a=0
LET k=360/ak
LET r=1.414
LET d=side/r^level
LET lev=level
SET COLOR 13
CALL move2(d,lev,a,x,y,k)
END SUB

SUB move1(d,lev,a,x,y,k)   !orthodox version (45 degree turns)
IF lev=0 THEN
CALL travelON(d,a,x,y)
ELSE
CALL turnLEFT(a,k)
CALL move1(d,lev-1,a,x,y,k)
CALL turnRIGHT(a,k)
CALL turnRIGHT(a,k)
CALL move1(d,lev-1,a,x,y,k)
CALL turnLEFT(a,k)
END IF
END SUB

SUB move2(d,lev,a,x,y,k)   !epicentric version (90 degree turns)
IF lev=0 THEN
CALL travelON(d,a,x,y)
ELSE
CALL move2(d,lev-1,a,x,y,k)
CALL turnRIGHT(a,k)
CALL move2(d,lev-1,a,x,y,k)
CALL turnRIGHT(a,k)
END IF
END SUB

SUB travelON(d,a,x,y)
OPTION ANGLE degrees
LET x2=x+d*cos(a)
LET y2=y+d*sin(a)
PLOT x,y;x2,y2
LET x=x2
LET y=y2
END SUB

SUB turnLEFT(a,k)
LET a=a+k
END SUB

SUB turnRIGHT(a,k)
LET a=a-k
END SUB