function mc_pi, n, no_loop=no_loop, seed=seed
r = 1. ;;; Circle with a unit radius
if keyword_set(no_loop) then begin ;to loop or not to loop? That is the Q.
    ;;; Generate x annd y coordinates as arrays
    x = randomu(seed, n)*2-r
    y = randomu(seed, n)*2-r
    ;;; Check to see how many points are inside the circle
    w=where((x^2+y^2) le r^2, incirc)
endif else begin
    incirc = 0.
    for i = 0, n-1 do begin
        ;;; Generate an x and y point
        x = randomu(seed)*2-r
        y = randomu(seed)*2-r
        ;;; Is it inside the circle?
        if x^2+y^2 le r^2 then incirc++
    endfor
endelse
;;; Calculate pi
pi = float(incirc)/float(n)*4.
return, pi
end