(phixonline)-->
with javascript_semantics
constant dt = 0.1
atom y = 1.0
printf(1," x true/actual y calculated y relative error\n")
printf(1," --- ------------- ------------- --------------\n")
for i=0 to 100 do
atom t = i*dt
if integer(t) then
atom act = power(t*t+4,2)/16
printf(1,"%4.1f %14.9f %14.9f %.9e\n",{t,act,y,abs(y-act)})
end if
atom k1 = t*sqrt(y),
k2 = (t+dt/2)*sqrt(y+dt/2*k1),
k3 = (t+dt/2)*sqrt(y+dt/2*k2),
k4 = (t+dt)*sqrt(y+dt*k3)
y += dt*(k1+2*(k2+k3)+k4)/6
end for