Chapter 9

1. What does the floor function do?

   Return the next lowest whole number.

2. What is the ABS of -3?

   3

3. What is the ATAN function?

   Inverse of the TAN function.

4. How would you write a program that can calculate a quadratic equation?

   PROGRAM PLC_PRG
   VAR
       a : INT;
       b : INT;
       c : INT;
       root1 : REAL;
       root2 : REAL;
   END_VAR
   root1 := ((-1 * b) + SQRT(EXPT(b,2) - (4*a*c))) / (2*a);
   root2 := ((-1 * b) - SQRT(EXPT(b,2) - (4*a*c))) / (2*a);

5. How would you write a program that can calculate 4 to the power of 3?

   EXPT(4,3)

6. What is the order of operations for a program?

   Parentheses, exponents, multiplication, division, addition, and subtraction.

7. What is the assignment operator?

   :=