1. “Operators” (i.e. “symbols”)
Overview: Specific Symbols that Represent Specific Actions
Arithmetic
Relational
Boolean
Output values

2. Overview: most Operators
There are 3 primary groups of operators
One programming operator is very different from its use in math:
1. ARITHMETIC +
Addition -
Subtraction *
Multiplication
/,\
Division ^
Exponentiation,
i.e. “To the power of”
2. RELATIONAL
<
strictly less than
>
strictly greater than
<=
less than or equal to
>=
greater than or equal to ==
is equal to ~=
is not equal to
3. BOOLEAN
&&
“AND” ||
“OR” ~
“NOT” =
“the assignment operator”

3. 4 * 5 -5 Overview, cont. Operators work on operands. Binary Operator
Requires two operands to work
4 * 5
operands
Multiplication operator -5
Unary Operator
Requires one operand to work
operand
Negative operator

4. kineticEnergy = 1 / 2 * mass * vel ^ 2
Overview, cont.
There are 2 types of operands:
Numerical 1, 3.5, -47
Logical true, false
Arithmetic (+, -, /, *, ^, =) and relational (<, <=, >, >= ,==, ~=) operators work with numerical operands
Numerical Operands
kineticEnergy = 1 / 2 * mass * vel ^ 2
Arithmetic operators
Assign operator: “place one or more values into memory”

5. Overview, cont. There are 2 types of operands:
Numerical 1, 3.5, -47
Logical true, false
Boolean (&&,||,~) operators work on logical operands
“ if this is true and this is false… do something”
if (it's raining outside) and (you have an umbrella)
go, you won't get wet
else
stay inside!
end

6. True, False, 1, and 0?!
True
False 1

7. 3. Relational Operators
Relational operators allow a comparison to be evaluated.
Is thrust_a greater than thrust_b?  True / False Is surface1 equal to surface2?  True / False? Is load1 less than or equal to load2?  True / False?
Examples:
thrust_a > thrust_b
Is thrust_a strictly greater than thrust_b?
radius <=0
Is radius negative or zero?
nb_attempts<= 3
Is the number of attempts less than or equal to 3?
3 >= nb_attempts
Is 3 greater than or equal to the number of attempts?
value ~= 2
Is value not equal to 2?

8. Relational Operators, cont.
***COMPARISON*** ==
y == 5 % “Does y hold the value 5?”
% “Is y equal to 5?”
Example:
menuChosen == 1 % did user choose menu #1 ?

9. Relational Operators, cont.
***COMPARISON*** ==
y == 5 % “Does y hold the value 5?”
% “Is y equal to 5?”
Example:
menuChosen == 1 % did user choose menu #1 ?
Assignment = % A numerical operator
y = 5; % “Store the value 5 in the % variable y”
Note that == and = are DIFFERENT!

10. Spaces or not?
When one relational operator is made up of 2 symbols (<=, >=, ~=, ==): KEEP THEM GLUED TOGETHER

11. Spaces or not?
When one relational operator is made up of 2 symbols (<=, >=, ~=, ==): KEEP THEM GLUED TOGETHER
Regardless of which operator is used, a space can be used before and/or after. All these are identical to MATLAB:
thrustA<=thrustB %no spaces anywhere
thrustA <=thrustB %1 space before the operator
thrustA<= thrustB %1 space after the operator
thrustA <= thrustB %1 space before AND after

12. 4. Boolean Operators
These operators take logical scalar values and perform some operation on them to yield a logical value
Two Boolean operators allow to COMBINE relational expressions
&& Logical AND
|| Logical OR
One Boolean operator allows to NEGATE the result
~ Logical NOT
“Negates”: turns true values into false, and false values into true

13. Boolean Operator #1: && “logical and”
Two & symbols (“Ampersand”), glued together
&&
Both relational expressions must be true for the combined expression to be true
X && Y yields true if and only if both X and Y are true
e.g. (3 < 5) && (8 >= 8) ?
(x < 1) && (x > 5) ?
x = 52.1;
(5.5 < x) && (x < 100.2) ?

14. &&, continued Use of parenthesis e.g. (3<5) && (8>=8) true
same as 3<5 && 8>=8 true
(x<3) && (x>5) false
same as x<3 && x>5 false
For sanity, at least use spaces before/after the operator!

15. True/False What is the result of the following statement?
(2 > 3) && (3 < 29.3)
True
False
Impossible to determine
(22 > 3) && (3 > 29.3)
(22 > x) && (x > 29.3)
True
False
Impossible to determine
(x<2) && (y>0)

16. True/False In other words, there are 4 options: F && T T && F F && F

17. Boolean Operator #2: || “logical or”
Two | (“pipe”) symbols, glued together ||
At least ONE relational expressions must be true for the combined expression to be true
X || Y yields true if either X or Y (or both) are true
e.g. (3<5) || (5>=8) ?
x = 4.2;
(x< 3) || (x > 5) ?

18. True/False What is the result of the following statement?
(2 > 3) || (3 < 29.3)
True
False
Impossible to determine
(22 > 3) || (3 > 29.3)
(22 > x) || (x > 29.3)
True
False
Impossible to determine
(x<2) || (y>0)

19. True/False Again, there are 4 options: F || T T || F F || F T || T

20. Priorities between Boolean Operators
Which operator has priority in the following?
* 1
Just like * has priority over + , && has priority over ||
What is the result of this statement?
x = 44.5;
y = 55;
(x<=50) || (0<y) && (y<40) ?
((x<=50) || (0<y)) && (y<40) ?
(x<=50) || ((0<y) && (y<40)) ?

21. Boolean Operator #3: NOT
One ~ symbol (“tilde”)
“NOT” : negates a value
Example:
x = true; %keyword is known to MATLAB
y = ~x; %y now has the value false
The value y entered by the user should NOT be between 4 and 9 cm, inclusive:
% Suppose the user enters 7.4 as a value for y
~(4<=y && y<=9) ?

22. 5. Operators: Result values
Type Operand type Result type Arithmetic: Numbers Numbers e.g. 5 * 3 15 Relational: Numbers Logical e.g. 5 < 3 false Boolean: Logical Logical e.g. ~true false true & false

23. Order of Operations Operator Priority Parenthesis () Highest
Exponentiation ^
Unary: -, NOT ~
Multiplication/division: * / \
Addition/subtraction:
Relational: <, <=, >, >=, ==, ~=
AND: &&
OR: ||
Assignment: =
Lowest