Before we give the complete syntax for an SGIF file, we finish the illustrative example that we started in Section 3.1.4 and Section 4.3 and show how to specify an input file appropriate for the problem of Section 2.5. The format is fairly similar to that for the SEIF file of Section 4. Once again, there are many possible ways of specifying a particular problem; we give one in Figure 5.2.
The file must always start with a GROUPS card, on which a name (in this case EG3) for the example may be given (line 1), and must end with an ENDATA card (line 10).
We next need to specify the names and attributes of any auxiliary quantities and functions that we intend to use in our high level description of the group functions. These are needed to allow for consistency checks in the subsequent high-level language statements and must always occur in the TEMPORARIES section of the input file. Line 3 indicates that we shall be using temporary quantities TWOP1 and the character R in the first field of this lines states that the quantity will be associated with a floating point (real) value.
We now make the actual definitions of the function and derivative
values for the nontrivial group type
used; we recall that there is a
single nontrivial group type PSQUARE and that its attributes
(name of group-type variable
and parameter) have been described in the
SDIF file set up in Section 3.1.4. This definition takes place
within the INDIVIDUALS
section. The presence of the character T
in field 1 of line 5 announces that the data for the group
type PSQUARE is to follow. All the data for this group must be
specified before another group type
is considered. We note that the
quantity 
occurs in both first and second derivatives
of the
group type function and so the auxiliary quantity TWOP1 is set
on line 6 to hold this value. The first field of a line on which such
an assignment is made contains the character A.
The value (line 7), its first derivative (line 8) and second
derivative (line 9) with respect to the group-type
variable are now given. A Fortran
expression for these values occurs in field 7 on
each of these lines; the lines contain the characters F, G
and H
respectively in field 1 for such assignments.
If there had been more than a single group type with one or more expressions in common, these expressions could have been assigned to previously attributed quantities in a GLOBALS section. This section would then have appeared between the TEMPORARIES and INDIVIDUALS sections.
