variable inside for loop with if and t variable

Hello, how can i use variable inside for loop?

t(1)=0;

dt=0.01;

tvege=1000;

y=zeros(tvege,1)

Xt=zeros(tvege,1)

for i=1:tvege

      aVARIABLE(i+1) =23950.*(( Xt(i))>0.1) +(10+10*exp(-0.5*( *t(i)*))).*((Xt(i))<=0.1);

      YVARIABLE(i+1)=5* *Xt(i)*;

      y(i+1)=y(i)+dt*( ( aVARIABLE(i) * ( YVARIABLE(i) - y(i) ))

      Xt(i+1)=Xt(i)+dt(y(i)-0.5)

end

so i get wrong results.....the code is working if i use constants for aVARIABLE and YVARIABLE but with my (i+1) thing and with t(i)....something goes wrong...so my euler with contants working but if i want to put dependent variables (.*WITH IF) in my for loop.....goes wrong.... how can i do that?

[Geoff Hayes]

baki - you will need to clarify what you mean by something goes wrong. Also, please provide code that is bug-free. The line

 aVARIABLE(i+1) =23950.*(( Xt(i))>0.1) +(10+10*exp(-0.5*( *t(i)*))).*((Xt(i))<=0.1);

has at least two errors in it.