comment AP 259;
	  procedure RK4n(x,xa,b,fxj,j,e,d,fi,n,l,pos); value fi,n,l,pos; integer j,n,l;
	  Boolean fi,pos; real b,fxj; array x,xa,e,d;
	  begin integer i,iv,iv0; Boolean fir,first,rej; real h,cond0,cond1,fhm,absh,
	    tol,fh,max,x0,x1,s,hmin,hl,mu,mu1; array xl,discr,y[0:n],k[0:5,0:n],e1[1:2];
	    procedure RKstep(h,d); value h,d; integer d; real h;
	    begin integer i;
	      procedure F(t); value t; integer t;
	      begin integer i; real p; for j:= 1 step 1 until n do y[j]:= fxj; p:=
	        h/y[iv]; for i:= 0 step 1 until n do begin if i != iv then k[t,i]:=
	        y[i] * p end end F;
	      if d = 2 then goto integrate; if d = 3 then begin for i:= 0 step 1
	      until n do x[i]:= xl[i]; F(0) end else if d = 1 then
	      begin real p; p:= h/y[iv]; for i:= 0 step 1 un*99*i