NOAA Paleoclimatology Program

Appendix B

B.1.Operator Precedence

Operator	Order
(	left
NOT	right
* /	left
+ -	left
< <= > >=	left
= != <>	left
AND	left
OR	left

In the operator precedence table, operators at the same level have the same precedence. Operators at the top of the table have the highest precedence. In other words, in expressions with no parenthesizes, these operations would be performed first before a operator with lower precedence.
Order determines whether an operation is performed left to right or right to left.

B.2 Operand Types

There are 4 types of operands in PaleoVu - Float, Long, Variable, and Boolean. Mixing these types and certain operations can produce valid results or errors. Following is a list of tables indicating operator, operand types and resulting value types.

Operators +, -, *

*Left Operand*	*Right Operand*
	Long	Float	Variable	Boolean
Long	Long	Float	Variable	Boolean/False a
Float	Float	Float	Variable	Boolean/False
Variable	Variable	Variable	Error	Boolean/False
Boolean	Boolean/False	Boolean/False	Boolean/False	Boolean/False

a. Where Boolean return types have a value, it does not matter what the operand values are, this is the value that is returned.

Operators / a

*Left Operand*	*Right Operand*
	Long	Float	Variable	Boolean
Long	Long	Float	Error	Boolean/False b
Float	Float	Float	Error	Boolean/False
Variable	Variable	Variable	Error	Boolean/False
Boolean	Boolean/False	Boolean/False	Boolean/False	Boolean/False

a. Divide by 0 errors are returned as an error.

b. Where Boolean return types have a value, it does not matter what the operand values are, this is the value that is returned.

Operators OR, AND

*Left Operand*	*Right Operand*
	Long	Float	Variable	Boolean
Long	Boolean/True a	Boolean/True	Boolean/True	Boolean/Right b
Float	Boolean/True	Boolean/True	Boolean/True	Boolean/Right
Variable	Boolean/True	Boolean/True	Boolean/True	Boolean/Right
Boolean	Boolean/Left	Boolean/Left	Boolean/Left	Boolean

a. Where Boolean return types have a value, it does not matter what the operand values are, this is the value that is returned.

b. When Left of Right are indicated for a Boolean value, the value of the left or right operand is returned regardless of the other operand value.

Operator =, <>

*Left Operand*	Right Operand
	Long	Float	Variable	Boolean
Long	Boolean	Boolean	Boolean	Boolean/False a
Float	Boolean	Boolean	Boolean	Boolean/False
Variable	Boolean	Boolean	Error	Boolean/False
Boolean	Boolean/False	Boolean/False	Boolean/False	Boolean

a. Where Boolean return types have a value, it does not matter what the operand values are, this is the value that is returned.

Operators <, <=, >, >=

*Left Operand*	*Right Operand*
	Long	Float	Variable	Boolean
Long	Boolean	Boolean	Boolean	Boolean/False a
Float	Boolean	Boolean	Boolean	Boolean/False
Variable	Boolean	Boolean	Boolean	Boolean/False
Boolean	Boolean/False	Boolean/False	Boolean/False	Boolean/False

a. Where Boolean return types have a value, it does not matter what the operand values are, this is the value that is returned.

Operator - (unary)

*Left Operand*	*Return Type*
Long	Long
Float	Float
Variable	Variable
Boolean	Boolean/False

a. Where Boolean return types have a value, it does not matter what the operand values are, this is the value that is returned.