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“Operators” (i.e. “symbols”). Overview: Specific Symbols that Represent Specific Actions Arithmetic Relational Boolean Output values. Overview : most Operators. There are 3 primary groups of operators One operator is very different in programming compared to math .

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Operators i e symbols

“Operators” (i.e. “symbols”)

Overview: Specific Symbols that Represent Specific Actions

Arithmetic

Relational

Boolean

Output values


Overview most operators
Overview: most Operators

  • There are 3 primary groups of operators

  • One operator is very different in programming compared to math


1 arithmetic operators
1. Arithmetic Operators

REVIEW

  • Arithmetic equations:

    variableName = equation ;

    • MATLAB executes the equation FIRST (following the order of operation from left to right), then stores the result in the variable on the left.

  • However, in the equation itself, MATLAB respects the Order of Operations:

    • 2+3*5 is the same as 2+(3*5), but different than (2+3)*5

    • val1*val2/val3^4 + val5/(val6+val7);

  • Remember the multiplication operator isn’t implied

    >>(2)(5)(5.5)+5(6/3) <enter> will crash MATLAB.


2 relational operators
2. Relational Operators

  • Relational operators allow a comparison to be evaluated.

    Is thrust_a greater than thrust_b?  True/false? 1/0?

    Is surface1 equal to surface2?  True/false? 1/0?

    Isload1less than or equal toload2?  True/false? 1/0?

  • Examples:


Vs operator
= vs. == operator

= operator: ASSIGNMENT

== operator: COMPARE

"Is this value equal to another"

  • "To give a value to"

THIS IS NOT A RELATIONAL OPERATOR!!

MATLAB is NOT checking the relation between x and 2


Spaces or not
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


3 boolean operators
3. Boolean Operators

  • These operators take logical values and perform some operation on them to yield a logical value (0 or 1)

  • 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


Boolean operators
Boolean Operators

“ 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

ifx<0 && y>0 && z>0 %if x negative and y and z positive

%do option1

else

%do option2

end


Boolean operator 1 and
Boolean Operator #1: && “and”

  • Two & symbols (“Ampersand”), glued together

    &&

  • Both relational expressions must be truefor the combined expression to be true

  • X && Y yields trueiff both XandY are true

    e.g. (3<5) && (8>=8) ?

    (x< 3) && (x > 5) ?

    x = 52.1;

    (5.5<x) && (x<100.2) ?


Continued
&&, 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!


True false
True/False

(2 > 3) && (3 < 29.3)

  • True (1)

  • False (0)

  • Impossible to determine

    (22 > 3) && (3 > 29.3)

  • True (1)

  • False (0)

  • Impossible to determine

(22 > x) && (x > 29.3)

  • True (1)

  • False (0)

  • Impossible to determine

    (x<2) && (y>0)

  • True (1)

  • False (0)

  • Impossible to determine

  • What is the result of the following statement?


True false1
True/False

F && T

  • True (1)

  • False (0)

    T && F

  • True (1)

  • False (0)

F && F

  • True (1)

  • False (0)

    T && T

  • True (1)

  • False (0)

  • In other words, there are 4 options:


Boolean operator 2 or
Boolean Operator #2: || “or”

  • Two | symbols (“pipe”), glued together

    ||

  • At least ONE relational expressions must be truefor the combined expression to be true

  • X || Y yields true if eitherXorY (or both) are true

    e.g. (3<5) || (5>=8) ?

    x = 4.2;

    (x< 3) || (x > 5) ?


True false2
True/False

(2 > 3) || (3 < 29.3)

  • True (1)

  • False (0)

  • Impossible to determine

    (22 > 3) || (3 > 29.3)

  • True (1)

  • False (0)

  • Impossible to determine

(22 > x) || (x > 29.3)

  • True (1)

  • False (0)

  • Impossible to determine

    (x<2) || (y>0)

  • True (1)

  • False (0)

  • Impossible to determine

  • What is the result of the following statement?


True false3
True/False

F || T

  • True (1)

  • False (0)

    T || F

  • True (1)

  • False (0)

F || F

  • True (1)

  • False (0)

    T || T

  • True (1)

  • False (0)

  • Again, there are 4 options:


Priorities between b oolean operators
Priorities between Boolean Operators

  • Which operator has priority in the following?

    1 + 1 + 0 * 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)) ?


Boolean operator 3 not
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

  • Example:

    • the value y entered by the user should NOT be between 4 and 9 cm included:

      %assume user enters 7.4 when asked for a value of y

      ~(4<=y && y<=9) ?


Order of operations of all operators
Order of Operations of ALL operators


Key ideas
Key Ideas

  • Vocabulary: operators, operands, arithmetic, relational, boolean, unary, binary, numerical, logical

  • Assignment vs. “is equal to” operator

  • Find the &, |, and ~ symbols on the keyboard

  • When does a && b && c evaluate the true?

  • When does a || b || c evaluate to true?

  • When does a && b || c && d evaluate to true?

  • Order of operations is respected when MATLAB executes any expression


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