Statements - Control Data Corporation 3300 Reference Manual

4.2.2
STATEMENTS
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A one-to-one correspondence is necessary between left and right parentheses
such that each left parenthesis is to the left of its corresponding right
parenthesis.
Arithmetic expressions may be evaluated according to paired parentheses.
Expressions within parentheses are evaluated first, and, within a test of
parentheses, evaluation proceeds from the least inclusive to the most inclusive
set. When parentheses are not used, or parenthesized expressions are at the
same level of inclusiveness, the following hierarchical order of operations is
implied:
Unary -
**
*
and /
+ and-
When the order of a sequence of consecutive operations is not on the same
hierarchical level completely specified by parentheses; the order of evalua-
tion is from left to right.
Arithmetic statements are ADD, COMPUTE, DIVIDE, MULTIPLY, and
SUBTRACT. They have several common features: data descriptions of
the operands need not be the same; any necessary conversion and decimal
point alignment is supplied throughout the calculation.
The maximum size of each operand is 18 decimal digits.
Operands may be COMPUTATIONAL, COMPUTATIONAL-I, or
COMPUTA TIONAL-2 items.
When the operands in arithmetic statements are not all the same mode, the
compiler must generate conversions.
In
the following conversions:
COMPUTATIONAL-2 to COMPUTATIONAL-I
COMPUTATIONAL-2 to COMPUTA TIONAL
COMPUTATIONAL-I to COMPUTATIONAL
the converted value may not fit in the resultant field. The most significant
digits could be lost making the result completely unreliable. To avoid this
situation, the user should specify the ON SIZE ERROR option (see OPTIONS,
4.4.2). He may also use MOVE statements prior to the arithmetic statements
to make the operands all the same mode.
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