ZXASCII
AUTO -1
PROG demos:3d/sinc
CHANGED FALSE
10 REM Sinc demonstration
20 REM Z=Sinc(Sqr(X^2+y^2))
25 SCREEN LOCK
 
30 np=200: 
 DIM pts(np*np,3)
 
40 a=0,f=1,xstep=20/np,ystep=20/np,xn=-10: 
 FOR x=1 TO np: 
    yn=-10: 
    FOR y=1 TO np: 
       pts(f,1)=x,
       pts(f,2)=y,
       n=PI*PYTH(xn,yn),
       pts(f,3)=SIN n/n: 
       f+=1,yn+=ystep: 
    NEXT y: 
    xn+=xstep: 
 NEXT x
 
50 PROJECT3D pts() TO dst() MOVE -np,-np,0 ROTATE a,a/2,a/3 SCALE 3,3,200: 
 PLOT dst(): 
 WAIT SCREEN: 
 CLS: 
 a+=PI/180: 
 GO TO 50