1. Ch 7-8 Arithmetic Logical Operators
© Fall 2004 Don Edwards and the University of South Carolina

2. 7 Arithmetic Basic operators (+,-,…)
Typical “calculator” functions (exp, log, sqrt, sum, prod, …)
Matrices
Elementwise and matrix operators
Be careful of object type
Maple users may be underwhelmed

3. 8 Logical Objects and Operators
TRUE or FALSE values
Logical operators (>,<,>=,!,…)
Subsetting and conditional execution
Compound (&,|,..) and sequential (&&,||,…) operators
With sequential operators, the second logical comparison can be skipped if the first is true. Not really evident in real time.

4. 8 Logical Operators as functions
xor
any, all, identical,…
Avoid == with numeric variables
Don’s old notes had an advanced discussion of testing equivalency of numeric variables. Class Exercise 3 touches on this topic as well.

5. 8 Conditional Execution
if{…} else if{…} else {…}
The if() statement works elementwise
Wait till Chapter 10: Iteration
ifelse()
Excel recoding
The syntax for if/else if/else is highly structured—very un-R like. Class Exercise 3 discusses ifelse()