[MATLAB数学相关] ［求助］ode45和循环问题

[suyc]

function dy = 0518(t,y)
dy = zeros(8,1);
kprisclb2=0.004;
ksclb2=0.01;
kpridclb2=0.0125;
kdclb2=0.5;
kas2=10;
kds2=0.01;
kpriamcm1=0.01;
kamcm1=2;
kimcm1=0.2;
ksclb5=0.01;
kpridclb5=0.02;
kdclb5=0.05;
kas5=10;
kds5=0.01;
kprissic1=0.02;
kssic1=1;
kdsic1=2;
kpridsic1=0.3;
kpri2dsic1=2;
kaswi5=0.01;
kpriaswi5=1;
kiswi5=0.01;
kpriiswi5=1;
jswi5=0.1;
kscdh1=0.02;
kdcdh1=0.02;
cdc14=0.02;
apc=1;
kprisclb5=0;
dy(1)=kprisclb2+ksclb2*y(7)-y(1)*(kpridclb2+kdclb2*y(6)*apc);
dy(2)=kprisclb5-y(2)*(kpridclb5+kdclb5*y(6)*apc);
dy(3)=kprissic1+kssic1*y(8)-y(3)*(kpridsic1+kpri2dsic1*(y(2)-y(5))+kdsic1*(y(1)-y(4)));
dy(4)=kas2*(y(1)-y(4))*(y(3)-y(4)-y(5))-kds2*y(4)-((kpridclb2+kdclb2*y(6)*apc)+(kpridsic1+kpri2dsic1*(y(2)-y(5))+kdsic1*(y(1)-y(4))))*y(4);
dy(5)=kas5*(y(2)-y(5))*(y(3)-y(4)-y(5))-kds5*y(5)-((kpridclb5+kdclb5*y(6)*apc)+(kpridsic1+kpri2dsic1*(y(2)-y(5))+kdsic1*(y(1)-y(4))))*y(5);
dy(6)=kscdh1-kdcdh1*y(6);
dy(7)=(1-y(7))*(kpriamcm1+kamcm1*y(2))-kimcm1*y(7);
dy(8)=(kaswi5+kpriaswi5*cdc14)*(1-y(8))/(jswi5+1-y(8))-(kiswi5+kpriiswi5*(y(1)-y(4)))*y(8)/(jswi5+y(8));
如果我想在自变量t执行到50次时，调整参数，譬如把参数“apc”调整为0.02，请问高手指点！