# Variable range()

Hello, I have the following code:

```
def f(a,b,c,x):
xtemp=a
for i in range(b,x):
xtemp=xtemp-xtemp*c
return xtemp
var('t')
plot(f(10000000,1,0.01,t),3,20)
```

and got the error

```
TypeError: range() integer end argument expected, got
sage.symbolic.expression.Expression.
```

I understand that range does nor support 'var' object, but how can I have a variable range in this kind of function?

Thank you Niles it works well for my needs