This is not the the DATA statement in a BASIC program. The function in
FORTRAN is to allow the programmer to set up initial values for variables before
program execution occurs. For example, the value of frequently used constants
could be initialised in this way:
Im each case the variable name is followed by a solidus (/), the value of the
variable, another solidus and separated from the next name by a comma.
It is most important, particularly with type declarations and array
declarations, to ensure that these are put in in the correct sequence before ANY
executable program statements.
A suitable order for most FORTRAN versions is:
. (executable statements)
This applies co both main program and all subroutine will
be required for most progcams (hank goodness!).
SUBROUTINES and FUNCTIONS
These are program sub-units which are called by the main program as required.
They do not occur in precisely the same form in most versions of (where
the GOSUB…RETURN statements have an approximately similar operation) – BBC
BASIC uses PROCeduces which are a closer approximation. There is an essential
difference between SUBROUTINES and FUNCTIONs in the way the main program uses
them, the SUBROUTINE is CALLed by name using the CALL statement and when the
program statements contained in it have been processed, control is passed back
to the gain program by means of a RETURN statement. Typical uses for a
subroutine are where a series of tables have to be set up or where graphical
data has to be displayed or a complicated expression has to be evaluated.
FUNCTIONs are used differently. The function name appears as one of the
variables in an assignment statement and the value of the function (at
calculated) is used in the evaluation of the assignment. For example, if the
value of pi is required for some calculations involving the area or
circumference of a circle and the version of FORTRAN you are using does not
supply this as one of its intrinsic functions, then a FUNCTION subprogram could
be written to provide it (only a dodo would actually do this but it is a good