command to create array and graph

Hi guys,

I am preparing for exams, doing practice questions and want to know if the commands I am using for a question are correct.

Matrix 3 rows, 5 columns

• 16 456 22 85 93
• 11 78 310 62 36
• 1 66 23 67 405

Is the command to create this matrix

a = [16 456 22 85 93;11 78 310 62 36;1 66 23 67 405] ?

how would I graph the 3rd row or column? how can the grid of the graph be set to visable and the x and y axis to be included?

thank you :)

Answer 1

[Geoff Hayes]

Laura - yes, the command

 a = [16 456 22 85 93;11 78 310 62 36;1 66 23 67 405]

will create the 3x5 matrix. To extract all of the elements of the third row, you can do

 a(3,:)

and to access all the elements of the third column, you can do

 a(:,3)

You can then plot this data however you want. See grid for displaying or hiding the axes grid lines.

[Laura McHugh]

Great help Geoff!! - I now understand how to extract use the rows and columns - how would I write command to turn on the grid to provide labels for the X ('sample') and y ('value') axes ?

[Geoff Hayes]

Glad to have been able to help, Laura. As for turning on the grid lines, please see the documentation at grid. Labels for the x and y axes, see Add Title, Axis Labels, and Legend to a Graph.

[Laura McHugh]

Thanks Geoff!!