matlab编程问题,已知函数表达式和数据,求表达式中的系数

t=[0.1,1.1,2.3,3.4,4.5,5.7,6.7]';
y=[0,94.0,84.0,77.0,69.0,62.0,56.0]';
ft_ = fittype('A*exp(-beta*t)*cos(w*t+phi)',...
'dependent',{'y'},'independent',{'t'},...
'coefficients',{'A','beta','phi','w'});
st=[-100 0.01 -pi 5]
[curve,goodness]= fit(t,y,ft_,'Startpoint',st)
figure
plot(curve,'predobs',0.95);
hold on,plot(t,y,'b*')
st =
-100.0000 0.0100 -3.1416 5.0000
curve =
General model:
curve(t) = A*exp(-beta*t)*cos(w*t+phi)
Coefficients (with 95% confidence bounds):
A = -143.8 (-219.6,-68.05)
beta = 0.135 (0.01584,0.2541)
phi = -2.131 (-2.379,-1.883)
w = 5.394 (5.259,5.529)
goodness =
sse:352.1786
rsquare:0.9377
dfe:3
adjrsquare:0.8754
rmse:10.8348