Open Watcom FORTRAN 77 Language Reference

Language Reference
Example:
INTEGER MARKS(40), N
REAL AVG, STDDEV, MEAN
PRINT *, ’Enter number of marks’
READ( 5, * ) N
PRINT *, ’Enter marks’
READ( 5, * ) (MARKS(I), I = 1, N)
AVG = MEAN( MARKS, N, STDDEV )
PRINT *, ’Mean = ’, AVG,
$ ’ Standard Deviation = ’, STDDEV
END
*
* Define function MEAN to return the average by
* defining the function name and return the standard
* deviation by defining a dummy argument.
*
REAL FUNCTION MEAN( A, N, STDDEV )
INTEGER A, N, I
REAL STDDEV
DIMENSION A(N)
MEAN = 0
DO 10 I = 1, N
MEAN = MEAN + A(I)
10 CONTINUE
MEAN = MEAN / N
STDDEV = 0
DO 20 I = 1, N
STDDEV = STDDEV + ( A(I) - MEAN )**2
20 CONTINUE
STDDEV = SQRT( STDDEV / (N - 1) )
END
12.4.1 Referencing an External Function
When an external function is referenced in an expression or a CALL statement, the following steps are
performed.
1. The actual arguments are evaluated.
2. The actual arguments are associated with the corresponding dummy arguments.
3. The external function is executed.
The type of the external function reference must be the same as the type of the function name in the
external function subprogram. If the external function is of type CHARACTER, the length must also
match.
12.4.2 Actual Arguments for an External Function
An actual argument must be one of the following.
272 External Functions
1. Any expression except a character expression involving the concatenation of an operand whose
length specification is (*) unless the operand is a symbolic constant.
2. An array name.
3. An intrinsic function name (must be the specific name) that has appeared in an INTRINSIC
statement.