CISC106-010, Fall 2007, Practice
Questions 9/24/2007
Instructions: To get most out of this
exercise, first try to solve the questions by yourself in the given order.
Then, check your answers by clicking here.
(1) Assume you have a file named subtract.m in the current directory
with the following content.
|
function result = subtract(x,y) result = x-y; |
What is printed to the
screen when you type the following MABLAB statements in the MATLAB command
prompt?
>> clear
>> a = 10;
>> b = 2;
>> subtract(a,b)
>> result
(2) Assume you have a file named subtract.m in the current directory
with the following content.
|
result = x-y; |
What is printed to the
screen when you type the following MATLAB statements in the MATLAB command
prompt?
>> clear
>> x = 10;
>> y = 2;
>> subtract
>> result
(3) Assume you have a file named subtract.m in the current directory
with the following content.
|
function result = subtract(x,y) result = x-y; |
What is printed to the
screen when you type the following MABLAB statements in the MATLAB command
prompt?
>> clear
>> a = 10;
>> b = 2;
>> result = subtract(a,b);
>> result
>> result
??? Undefined function or variable 'result'.
This is the case because, result is a local variable to the function subtract and is not visible
in the current workspace.
>> result =
>>
>> 8
This is the case, because x
and
y are two
variables defined in the current workspace. Entering the name of the script
M-file (without the .m part), the script is executed and a value for the new
variable result is calculated. Since subtract.m is a script M-file, new
variable result is added into the current workspace after running
the script subtract.
>> result =
>>
>> 8
There are two variables
named result in this question: (1) The output variable of the function
subtract. The output variable result
is only
visible inside the function subtract. (2) The other variable
result is
defined in the current workspace. The value returned by the function subtract is assigned as the value
of the result in the current workspace.