We shall write if *f*^{(r)}(*t*) is continuous (that is, ).
If then . (It
is not necessary that each of the functions *f _{1}* and

- Example 1:
(r=0,1,2,...) but . We may introduce the order
*r*=-1 and write . - Example 2:
(8) (9)

Is it true that The answer is: yes. Is it true that The answer is: no, however .(It easily may be derived that has a continuous
derivative at the point *t*=0).

1/13/1998