Ploting & Inner Functions

Question 1

How can we graph an XY relationship?

Answer 1

By using the command:

plot(x, y)

Question 2

How can we get the maximum or minimum value of an array?

Answer 2

max(array) or min(array?

Question 3

How can I get help for finding functions?

Answer 3

Click Fx on the command line and use the search bar for finding whatever function you want.

Question 4

How do we get information about what a function does?

Answer 4

Use the command “help”. For instance:

help min —> will tell you everything you need you need to know about the function min.

Question 5

Another way to obtain documentation from the original source?

Answer 5

Use the following:

doc function —> This will open the official documentation from matlab

Question 6

How do we get the index where the max or min is located?

Answer 6

[maxVal, I] = max(y)

Question 7

How do we define functions in the same way as we do in math? As in, with the argument and all?

Answer 7

We use “anonymous functions” like this:

y = @(x) (function def)

y = @(x) (x+2).^2

Question 8

How to create a plotting environment?

Answer 8

Use figure(#number)

Question 9

How can I plot several graphs on a same figure?

Answer 9

By plotting and then holding on, like this:

plot(x,y)
hold on
plot(x,z)

Question 10

How to provide labels to the axis?

Answer 10

xlabel(“name of the label”)
ylabel(“name of the label”)

Question 11

How can we add titles to graphs?

Answer 11

Using title(“name”) command

Question 12

Activate grids?

Answer 12

Grid on

Question 13

How can we add legends?

Answer 13

With the legend(“name”) command

Question 14

How can I limit the axes?

Answer 14

xlim([a b])
ylimit([a b])

Question 15

How can I fill up discrete points so the can look continuous?

Answer 15

Put markers before the color, like for instance:

plot(x, y, “- - g*”)

It will add dashes to fill up

Question 16

How can I plot different images in a single figure but in individual plots?

Answer 16

Use the subplot command:

figure(1)
subplot(m, n, #position)

Question 17

How does matlab returns true or false statements?

Answer 17

With 1 for true and 0 for false.

Question 18

How can we perform logical comparisons between elements from an array/matrix with a single element?

Answer 18

Matlab makes it easier by simply comparing the array/matrix with that element:

A > 2

Here, if A is an array/matrix, it will check if every element is greater than 2 and it will return an array of the same size of A with 0s and 1s.

Question 19

How can I add or multiply all the elements of an array?

Answer 19

Using sum(A) or prod(A)