[求助]怎么用ode45解微分方程组？

用怎么解微分方程组呀？急急急！这种情况是怎么回事？
clc
k0=3.3*10^7;

p.g=6.0*10^7;
p.t=10;
p.sp=1.0*10^-12;
w=3.5*10^5;
m=0.04;
p.ip=0.002;
p.k=k0*(1-m*sin(w*t));
%fun4512.m
function dydt=fun 4512(t,y)
dydt=[-p.k*y(1)+p.g*y(1)*y(2)+sp;-1/p.t*((1+p,ip+y(1)^2)*y(2)-p.ip+1];
[t,y]=ode45(@fun4512,[0 0.04],[0,0.007]);
figure(1)
plot(t,y(1,:))

??? Error using ==> feval
Undefined function 'fun4512'.

Error in ==> C:\MATLAB6p1\toolbox\matlab\funfun\private\odearguments.m
On line 104 ==> f0 = feval(ode,t0,y0,args{:});

Error in ==> C:\MATLAB6p1\toolbox\matlab\funfun\ode45.m
On line 158 ==> [neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0, args, ...

Error in ==> C:\Untitled.m
On line 11 ==> [t,y]=ode45(@fun4512,[0 0.04],[0,0.007]);