Fortran Expression and I/O Statement

Real & Complex Expressions

Real Expressions

There are following rules to express the Real expressions:

1) A signed or unsigned real variable name or real constant is an expression.

Example:

-A, 3.8, 2.0 etc.

2) A real expression connected by an arithmetic operator to an unsigned real variable name or an unsigned real constant is a real expression.

Example:

-A +B *c, A/B etc.

3) A real expression enclosed in parentheses is a real expression.

Example:

(-A +B *c)

4) Two real expression connected by an arithmetic operator is a real expression.

Example:

A + B + AB

5) A real expression may be exponentiatede by an integer expression to form a real expression.

Example:

B ** I, (A +B) ** (I + J) etc.

Now users can easily write the arithmetic expression according to the rule of Fortran.

Example:

a3 - b2 + 3ab is written in Fortran language as: A***3 - B**2 + 3*A*B

Complex Expressions

Complex Expression in arithmetic expressions are formed by using complex quantities.

Example:

Consider A1, A2, A3 are declared as complex then it will be written in program as:

COMPLEX A1, A2, A3

If A1 = (1.5, 2.5), A2 =(2.0, 3.5) and A3 = (1.0, 2.0) then Fortran expression for the evaluation (1.5, 2.5) + (2.0, 3.5) - (1.0, 2.0) will be A1 + A2 -A3. Similarly other examples can be also written.

Example:

- IC * IA +IB

Here IC, IA, IB are unsigned integer variable and -, +, and * are arithmetic operators.

3) An integer expression enclosed in parentheses is an integer expression.

Example:

( -J * K +I) is an integer expression.;

Note: Two arithmetic operators should not occur in succession in an integer expression.

This is wrong to express:

Example:

IC -* IA