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| Figure 3 . Floating point errors. |
|---|
>>>10/3 + 20/3
10.0 |
However, in this case, Python returned an answer of 10.0, indicating that the answer is accurate to three significant figures. This is not really thecorrect answer, but as a practical matter, it may be the best answer. I will leave that for you to decide.
Go back to Question 11
Probably not. Floating point arithmetic often suffers from speed penalties. In addition, integer arithmetic produces exact results while floating pointarithmetic usually produces approximate results (although the approximations may be very close to being exact in many cases) .
Go back to Question 10
Floating point usually provides the greater range for storage of numeric values.
Go back to Question 9
The assignment operator causes the value of its right operand to be stored in the memory location identified by its left operand.
Go back to Question 8
An example of such a program is shown in Figure 1 . Note that the names of the two variables have the same letters, but different case.The fact that the two variables are different variables is illustrated by the fact that each is assigned a different value. The sum of the two variablesdemonstrates that the two variables contain different, and correct, values.
| Figure 1 . Same letters, different case. |
|---|
>>>aX=10 # this is one variable>>>Ax=20 # this is a different variable>>>aX+Ax
30>>> |
Contrast the above result with the program in Figure 2 where a variable whose name contains the same letters and the same case isused twice.
| Figure 2 . Same letters, same case. |
|---|
>>>ax=10>>>ax=20>>>ax+ax
40>>> |
All the program in Figure 2 accomplishes is the assignment of two different values to the same variable. The secondassignment overwrites the value previously assigned to the variable. The program then adds thevariable to itself using its current value of 20 producing a result of 40 (instead of 30 as in the previous example) .
Go back to Question 7
False. Variable names must begin with a letter or underscore character.
Go back to Question 6
Use meaningful variable names for which the spelling is obvious, such as theOverheadRate .
Go back to Question 5
Several different kinds of problems can result from making typing errors that result in misspelling the names of variables. These errors usually result inprograms that produce incorrect results without warning.
Go back to Question 4
False. Variable declarations are not required in Python. All that is required to cause a variable to come into existence is to invent a new name fora variable and assign a value to it.
Go back to Question 3
False. Python is not a strongly typed language. From a pure technical viewpoint, the Python programmer rarely needs to be concerned about type.
Go back to Question 2
False. The value of a variable is intended to change during the execution of the program. The value of a constant (which I haven't discussed so far in this collection) is not intended to change.
Go back to Question 1
This section contains a variety of miscellaneous information.
Financial : Although the Connexions site makes it possible for you to download aPDF file for this module at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, youshould be aware that some of the HTML elements in this module may not translate well into PDF.
I also want you to know that, I receive no financial compensation from the Connexions website even if you purchase the PDF version ofthe module.
In the past, unknown individuals have copied my modules from cnx.org, converted them to Kindle books, and placed them for sale onAmazon.com showing me as the author. I neither receive compensation for those sales nor do I know who does receive compensation. If youpurchase such a book, please be aware that it is a copy of a module that is freely available on cnx.org and that it was made andpublished without my prior knowledge.
Affiliation : I am a professor of Computer Information Technology at Austin Community College in Austin, TX.
-end-
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