' - - File: XIIIb; IVP for first order differential equation: X'(t)  = F{t,x}

F{t,x} = -3x                                           ' Exact Solution: X{t} = 4e^(-3t)
to = 0  :  tf = 4 :  xo = 4
IVP[F, {to, tf, xo}{1.05,0.001}]
