Table of Contents
Advertisement
Arithmetic Statements
Expressions
Operation Symbols'
18
Example:
Of variables that are subscripted:
A(})
K(3)
B(I, J)
I ( 4,2)
BETA
(}-2 ,K+4)
In the last item in the example above, the object program computes the
value of the two-dimensional subscript by subtracting 2 from the value of
J
and
adding 4 to the value of K.
The numerical calculations to be performed in the object program are defined
by arithmetic statements.
FORTRAN
arithmetic statements closely resemble conven-
tional arithmetic formulas. They contain a variable to be computed, followed by
an
=
sign, followed by an arithmetic expression. For example, the arithmetic
statement
Y
=
A - SIN(B)
means "replace the value of the variable on the left side of the equal sign with the
value of the expression on the right side of the equal sign." In a
FORTRAN
program,
the equal sign means "is to be replaced by" rather than "is equivalent to."
The meaning of the equal sign is important in
FORTRAN.
Earlier in the manual
we learned that each variable in the obJect program is assigned a specific location
in storage that contains the data you have named. As an example, assume a fixed
pOint variable named
NUMBR
has the value of
6.
The statement
NUMBR
=
NUMBR
+
2
would cause the object program to take the value of
NUMBR,
which is
6,
increase it
hy
2,
and then set the result
8
as the new value of
NUMBR.
Format:
"a
=
b"
a is a variable and may be subscripted
b is an arithmetic expression (explained later)
Example:
A=B+C
D(I)
=
E(I)
+
2.-F
An expression in
FORTRAN
consists of a series of constants, variables, and functions
(explained later) separated by parentheses, commas, and/or operation symbols,
so as to form a mathematical expression. Expressions appear on the right-hand
side of arithmetic statements.
Five basic operations can be used in
FORTRAN:
addition, subtraction, multiplication,
division, and involution (raising to a power). These operations are represented in
FORTRAN
by the following symbols:
+
*
/
**
addition
subtraction
multiplication
division
involution
Advertisement
Table of Contents
