CS 1401, Quiz 6

Date: Monday, October 16, 2006
Name (please type legibly, ideally in block letters): ______________________________________________________________________

1. Mark what is covered and what is not covered in Chapter 8:

2-4.

2. Write a method named ex24 for computing the cubic root of the sum of two given real numbers x and y. Hint: a cubic root of a number z is equal to the number z raised to the power 1/3.

3. Call your method ex24 in the main method to compute the cubic root of a + b, where a = 3.0 and b = 5.0. (You do not need to write the entire main method, just the part that assigns values to a and b and calls your method.)

4. Trace, step by step, how the computer will perform the needed computations, and check that the result is indeed correct.


Solution:

public double ex24(double x, double y){
  double z = x + y;
  return Math.pow(z,1.0/3.0);}

in the method main:

double a = 3.0;
double b = 5.0;
double c = ex24(a,b);

Tracing:

first,

 ---------    ---------
|   3.0   |  |   5.0   |
 ---------    ---------
    a             b

 ------------------------
|  --------    --------- |
| |   3.0  |  |   5.0   ||
|  --------    --------- |
|     x            y     |
|------------------------|
|      ----------        |
|     |    8.0   |       |
|      ----------        |
|          z             |
 ------------------------
      ex24


 ---------
|   2.0   |
 ---------
    c