exm044_5.m

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%exm044_5.m
dt=0.1;t=(0:dt:10)';
y=exp(-0.8*t.*abs(sin(t)));
ss=dt*cumsum(y);						%矩形法求积
ss10=dt*sum(y);ssend=ss(end);		%sum所给结果就是ss(end)
st=cumtrapz(t,y);					%梯形法求积
st10=trapz(t,y);stend=st(end);	%trapz所给结果就是st(end)
disp([blanks(5),'sum',blanks(6),'cumsum',blanks(4),'trapz',blanks(5),'cumtrapz'])
disp([ss10,ssend,st10,stend])
clf
plot(t,y,'b:',t,ss,'r-',t,st,'r.')
legend('y(x)','cunsum','cumtrapz',0)  
shg