ABSTRACT
The interest earned on money invested in a deposit account is normally paid at set regular intervals. Calculations of the return are therefore usually made with respect to specific time intervals. For example, Figure 7.1(a) shows the amount of money in a deposit account at any given moment in time assuming an initial deposit of £1,000 and interest credited at the end of each year at a rate of 10%. There is not a continuous relationship between time and the total is a at the end of when the interest
on the account is paid. This is an example of a ‘discrete’ function. Between the occasions when interest is added there is no change in the value of the account.
