Differential Equation

[William Christopher Carleton]

I'm new to Octave and have tried to set up a simple differential equation that 
demonstrates variable behaviour as a result of a constant 'r'.

octave:1>function osc=f(x,t);
> osc = -1.01*x;
> endfunction

octave:2> x0=1000
octave:3> t=linspace(0,100,100)
octave:4> x=lsode("f",x0,t)
octave:5> plot(t,x)

The above equation should demonstrate an increasing oscillation, but instead 
plots as an exponential decay. What have I done incorrectly? Thanks,

Chris