Read the signal data stored in the file and create a program that displays the waveform

Hi Im new to matlab. Please help me. I want to read the signal data stored in a mat file and create a program that displays the waveform. And I want to display data for a specified particular interval. The signal data is from a sine wave. I have tried to use the load function but I dont know how to use it to plot the graph.

[dpb]

Well, you don't use load to plot the data, but the plot function might be of interest...<plot()>

[Cynthia Lucy]

Thank you so much for your comment @dpb. I didnt use load to plot the data, I use it to read the data file. Then, I use the plot function to plot the data but it doesnt seem to work. On the command window an "error: binary operator '*' not implemented for 'scalar' by 'scalar struct' operations" came out. I dont really understand what it means. Here I attached the programme file. Could you please explain to me what is wrong and what should I do. I really appreciate your help.

[dpb]

From the documenation on load the form you used of assigning the result to a variable

S = load(___) loads data into S, using any of the input arguments in the previous syntax group.

• If filename is a MAT-file, then S is a structure array.
• If filename is an ASCII file, then S is a double-precision array

The error about "scalar struct operations" is the clue your variable x is structure, not the array you think it is.

Type

whos x

at the command line and see what it returns.

The fix is to use

load('sec2Harmonics.mat');

which will leave whatever is the variable that was used in the workspace when the .mat file was saved in your workspace.

To see what that was/is use

whos -file sec2Harmonics.mat

[Cynthia Lucy]

Thank you so much @dpb! I have got the sine wave that I want to display. You explained it so well it really helps me a lot. Have a great day.

[dpb]

Moral -- post the actual code and error(s) you get first go 'round -- we only know what we're told; we can't see your terminal from here and so don't know that you did move on to the next step and had an error--all we knew was that you used load and wrote "I have tried to use the load function but I dont know how to use it to plot the graph." which leaves the impression you might have thought somehow MATLAB was to automagically plot something when it was load 'ed.

[Cynthia Lucy]

Thank you @dpb for the tips. I'll post a question along with the details next time.