DER="0"
 SRC="img279.png"
 ALT="$y_k$">.

<P>
Any component in  a range vector  not specified takes a default value.
The default   value for the components  of  each vector   is initially
infinite. This default may be changed  using  a card
whose third field
contains the string  <TT>'DEFAULT'</TT> as mentioned above.   On  such  a
card, the default value for the vector in field&nbsp;2  is given in field&nbsp;4
whenever field&nbsp;1  is blank
or contains the   character <TT>X</TT>.  If
field&nbsp;1  contains