5.3: Order of Operations
- Page ID
- 54257
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Fortran follows the standard mathematical order of operations or precedence of operations. That is, multiplication and division are performed before addition and subtraction. Further, in accordance with mathematical standards, the exponentiation operation is performed before multiplication and division.
The following table provides a partial summary of the basic Fortran 95/2003/2008 precedence levels:
| Precedence Level | Operator | Operation |
|---|---|---|
| 1st | - | unary - |
| 2nd | ** | exponentiation |
| 3rd | * / | multiplication and division |
| 4th | + - | addition and subtraction |
For operations of the same precedence level, the expression is evaluated left to right. Parentheses may be used to change the order of evaluation as necessary. For example, declaring the variables ans1, ans2, num1, num2, and num3.
integer :: ans1, ans2, num1=20, num2=50, num3=10
and calculating the ans1 and ans2, as follows:
ans1 = num1 + num2 * num3 ans2 = (num1 + num2) * num3
will set to ans1 to 520 and ans2 to 700 (both integers).