programming exam

Select ONLY the functional answers for how one might evaluate if x is greater than 6

x>6

Suppose you have a matrix A, defined by the following:

A = \[3 4\]

Write the output of the following command:

A >= 4

0 1

When declaring a function parameters are defined after the function and between the

Parentheses

Suppose you have a scalar . Write the conditional to test if is greater than or equal to 6.

c>=6

Data abstraction has some important features that we discussed.  Select *all* of the following features and statements that are true of data abstraction.

\-the process of considering a variable independently of its associations

* Matlab abstracts the type or variable for us meaning an assighnemnt of an integer is the same as an assignment of a string
* done with one assighnment
* removes uits related to a variable

Suppose you have a matrix X, which is a three by three matrix (a square).  Enter the command to calculate the element-wise third power of X.

X.^3

Suppose you have a three by one matrix , and another three by one matrix . To find the element-wise product (multilpication) of these two, one would use the following

A.\*B

uppose you have a three by one matrix , and a scalar . To find the element-wise sum (addition) of these two, one would use the following

A+B

Suppose you have a three by one matrix , and a scalar . To find the element-wise product (multilpication) of these two, one would use the following

A\*B

Suppose you have a scalar created by the following command:

d = rand(1,1)

Write the command to evaluate if d is lesser than 0.5.

d

Suppose you have a three by one matrix , and another three by one matrix . To find the element-wise different (subtraction) of these two, one would use the following

A-B

When writing a function, we need to start with the following on the first line (assuming one input and one output):

function \[returnOne\] = functionName(inputOne

Select all traits of both a for and while loop that we discussed in class.

* All **for** and **while** loops have an "exit strategy," or a means of determining it's time to stop looping.
* All **for** and **while** loops have a starting line that includes the condition test.
* All **for** and **while** loops have an ending line.
* All **for** and **while** loops have additional "stuff," or code, in the middle.

True or False: Functions allow us to take complex problems, and break them into smaller, and more manageable parts.

true

A **for** loop steps through a *predefined* number of iterations.

true

True or False: The workspace of a function is available to the user or the calling script/function at all times, during and after the function runs.

false

True or False: All functions must include the function declaration, defining that a function is to follow.  This looks like:

\
function \[values\] = functionName(parameters)

true

True or False: The help function in Matlab will return the first block of comments in the file, which is typically put right after the function declaration.

true

Assume the following function exists folliowing this structure:

\
function \[A, B, C\] = thisFunctionExample(someInput)

\
And suppose that you want to "save" value B.  To do so, you would call the function as follows:

\
B = thisFunctionExample (theInput)

false

A **for** loop inherently runs some *undetermined* number of times, until an exit condition is met.

false

Which of the folloing is how we would structure a **for** loop in Matlab?

for i = startingNumber : endingNumber

     % do something

end

rue or False: Formally, functions operate in their own workspace.

true

A **while** loop steps through a *predefined* number of iterations.

false

Assume the following function exists folliowing this structure:

\
function \[A, B, C\] = thisFunctionExample(someInput)

\
And suppose that you want to "save" all of the return values.  To do so, you would call the function as follows:

\
\[A, B, C\] = thisFunctionExample(theInput)

true

e talked about two types of iterations, while and for.

true

True or False: Functions ***can return output***, passing information back to the user or other script/function that called it.

true

Let's talk about how we write a function.

True or False: We can write functions inside the Matlab editor window (or a seperate text editor).

true

True or False: Formally, functions take input via values, and provide output via parameters.

false

Assume the following function exists folliowing this structure:

\
function \[A, B, C\] = thisFunctionExample(someInput)

\
And suppose that you want to "save" value A.  To do so, you would call the function as follows:

\
A = thisFunctionExample (theInput)

true

A **while** loop steps through each iteration until some condition is met and causes it to exit.

true

True or False: Formally, functions create, and then destroy all variables used while running the function.

true

True or False: Functions ***can take input***, which are passed to the functions as parameters.

true

Which of the folloing is how we would structure a **while** loop in Matlab?

\n while (someCondition)

     % do something

end

As a good practice, the second line in your function should include:

\
% the help info,

% documentation on how to use the function,

% what it does,

% author information

% and anything else relevant that the user of your function needs to know.

true

A **while** loop inherently runs some *undetermined* number of times, until an exit condition is met.

true

\n A **for** loop steps through a fixed set of values, iterating once for each value, and then exits.

true

T/F: the horizontal axis on a 2d scatter plot is generally (pretty much always) the independent variable.

true

Files allow us to save data (information) into long term storage.  But to save any data, we need to do some key things.  What key things did we discuss in class? 

* Agree on a format
* Read the data out in that same format
* Write the data in that format
* What was the question again?

T/F: the vertical axis on a 2d scatter plot is generally (pretty much always) the dependent variable.

true

If bytes are made up of bits, why bits?  Why a single 1 and 0?

A bit is the smallest unit of information we can make.

\n By using computer programs, a person can do the several things to a file.  What of the answers below are things one can do to a file?

* save
* close
* open
* change
* read

T/F: Bytes are sets of 8 bits together.

true

Suppose we have a set of data with four different measures in it.  One of these measures though, can be thought of as a categorical measure, while the others are continuous measures.  How did we plot something like this in class?

* we used both a hold on and an iteration
* we plotted each variable on a sperate axis, three of them
* each category received a different marker type and color
* we used plot3()

Of the regular file type, there are two basic format types.  These are?  Select the two.

text and binary

We talked about several (6) different file types, but noted that we're going to use one of them in this class.  All of our discussion has been around this one type.  Which type is this?

regular

Select all featues that are true for a Matlab **struct** data type.

* elements indexed by feild name
* indexed by #
* hold any basic data type in any location
* \

elect all featues that are true for a Matlab **cell array** data type.

* hold any basic type of data in any location
* indexed by number
* \

T/F: A Matlab **table** is similar to a spreadsheet table (Excel, Number, Gnumeric, etc), in that one can have named columns, and each row is another line of data.

true

integer

stores whole numbers

float

stores decimal value

matrix

For storing row and column type data, that is all a numeric (integer, float) value of some sort

character

a single letter or special character

string

a set of letters such as words

table

For storing row and column type data, where the data in each column is all the same type, but columns can be different types from each other.  Each column is named.

cell array

For storing row and column type data, where the data in each column doesn't have to be the same type, and columns can be different types from each other.  Each element is indexed by number.

struct

\n For storing data that is indexed by a fieldname, and can be mixed basic data types.  This advanced data type is best for sets of data that have different sizes.

Figures, such as scatter plots or line graphs, are nearly useless without additional context.  We went through this context in detail.  What additional things do we need to add to our figures to make them useful?

y-azis labe

x-axis label

legend

title

T/F: If files are sequences of "chunks" of data in a linear array, those "chunks" are bytes for text files.

true

What is the first part of a binary file called, the part that tells the operating system what kind of file this file is?

header

Why do we plot data, as opposed to just putting everything in a table?  Select all that apply.

* to see bigger picture and understand more quickly
* To better understand trends and patterns, connecting the independent and dependent variable when appropriate.
* Because I can't read binary like Neo, or even tables that are hundreds to millions of cells large, but I can get a good understanding of what's there from an image.

Matlab supports changing detailed properties of plots using the following functions, select all that are true.

dot,

get and set,

adding in the extra property (like MarkerSize) to the plot command when first calling it.

dot

(oop, fieldname) indexing

Select all featues that are true for a Matlab **table** data type.

* can hold any basic data but need to be the same type in the same column
* indexed by column name
* indexed by number
* \

\n T/F: A Matlab **cell array** is like a spreadsheet (Excel, Numbers, Gnumeric, etc), in that each cell contains a number (integer, float) or text (character, string), but it cannot store aything else (other data types).

false

When we work with a file on our computer, we're actually only working with a peice of software that is working with the low level aspects of the file.

true

What is a csv?

a comma seperated vale text file

T/F: A Matlab **struct** is the same as a spreadsheet table (Excel, Number, Gnumeric, etc), in that each cell arranged by row and column and is a container for one and only piece of data.

false

After plotting your data, you could stand back and squint to see what trend you see between the independent and dependent axes, or, you could find a trendline!  What's steps are typically needed to add a trendline on to your plot?

Element

A single value or item I. The matrix

Square matrix

A matrix that has the same number of Rowan’s as it has columns

Row vector

A matrix that has a single row

Column vector

A matrix that has a single columb

Array

A matrix with one dimension. Either a row or column vector

Scalar

A 1x1 matrix

Write a column vector

A=\[1,2,3\]

Make a row vecor

B=\[4;5;6\]

Make a square matrix

C=\[7,8;9,10\]

How to find dimensions of a matrix

Size(A)

Find certain elements of a matrix

D(1,2)

Replace element in matrix

D(1,2)=5

Indexing all

D(1,:)

Elements all from this to that

D(1,2:3)

Logical 1

True

Logical 0

False

Not equal to

\~=

Equal to compare

Common types of 2d plots

Scatter, line

Outlier

Usually an error

Scatter plot

* points scattered on the plot

Lien graph

Has line connecting data points

Bar graph

Represent a specific quantity

\
Hard to see trends

\
X-axis not continuous

Code scatter plot

Scatter (x,y)

Hold on

Used to plot things on same window

Multiple separate plots

Tiledlayout (2,1)

\*type next time before each plot

Plot color

Plot(x,y, ‘b’)

&

Find logical and

|

Find logical or

\~

Find logical not

Ciel

Rounds up

Floor

Rounds down