pro example

; Here is another program of IDL examples

x = findgen(100)		;an array: [0,1,2,...99]

for i = 0, 5 do begin		; a FOR loop
   read,'Type the period of the sine wave (5-100) ',P
   y = sin(!pi*x/P)		; (!pi = 3.141..)
   plot,x,y,title = 'Sine wave of Period: '+string(P)
endfor				; end of for loop

dummy = '' 
print,''
read,'Hit return to see some random data ',dummy
data = 5. * randomn(seed,20)	; 20 random points
print,data
print,'The average is ', mean(data)
print,'The standard deviation is: ',stdev(data)

print,''
read,'Hit return to see a 2D bessel function ',dummy
x2 = findgen(100)/5		; an array going from -10 to +10
y2 = beselj(x2)			; the bessel function
yy = [reverse(y2),y2]
plot,x2,y2,title = 'J Bessel Function'

read,'Hit return to see some 3D Bessels!',dummy
shade_surf,yy#yy	; # means matrix multiply by the way.

end				; end program