Open Watcom FORTRAN 77 Language Reference

Expressions
Example:
(123,0)
(-753,12.3)*2
-(12,-12.4)-(1.0,.2)
A double precision complex constant expression is an arithmetic constant expression in which at least one
constant or symbolic constant is of type COMPLEX*16 and all other constants or symbolic constants are of
type COMPLEX*16, DOUBLE PRECISION, REAL or INTEGER. If there are no constants or symbolic
constants of type COMPLEX*16 in a constant expression, the type of the constant expression will be
COMPLEX*16 if it contains at least one constant or symbolic constant of type COMPLEX and at least one
constant or symbolic constant of type DOUBLE PRECISION. Open Watcom FORTRAN 77 supports this
type of constant expression as an extension of the FORTRAN 77 language.
Example:
(123,0D0)
(-753,12.3D0)*2
-(12D0,-12.4)-(1.0,.2)
7.1.4 Data Type of Arithmetic Expressions
Evaluating an arithmetic expression produces a result which has a type. The type of the result is
determined by the type of its operands. The following table describes the rules for determining the type of
arithmetic expressions. The letters I, R, D, C and Z stand for INTEGER, REAL, DOUBLE PRECISION,
COMPLEX and COMPLEX*16 respectively. An entry in the table represents the data type of the result
when the operands are of the type indicated by the row and column in which the entry belongs. The
column represents the type of the operand to the right of the operator, and the row represents the type of the
operand to the left of the operator. The table is valid for all of the arithmetic operators.
op I*1 I*2 I*4 R D C Z
I*1 I*1 I*2 I*4 R D C Z
I*2 I*2 I*2 I*4 R D C Z
I*4 I*4 I*4 I*4 R D C Z
R R R R R D C Z
D D D D D D Z Z
C C C C C Z C Z
Z Z Z Z Z Z Z Z
Notes:
1. I*1 represents the INTEGER*1 data type, I*2 represents the INTEGER*2 data type, and I*4
represents the INTEGER or INTEGER*4 data type.
2. The data type of the result obtained by dividing an integer datum by an integer datum is also of
type INTEGER even though the mathematical result may not be an integer. This result is called
the integer quotient and is defined as the integer part of the mathematical quotient.
3. Open Watcom FORTRAN 77 supports the double precision complex data type
(COMPLEX*16) as an extension of the FORTRAN 77 language. Combining an operand of type
DOUBLE PRECISION with an operand of type COMPLEX yields a result of type
COMPLEX*16.
Arithmetic Expressions 177