how to find the period for the 0.2s,0.8s,1s and 2s ?

I succesfully run the program when the period is equal to 0.4 . but when i tried 0.2,0.8,1 and 2s . i got error. can anyone identify why is it wrong ?

When period = 0.4s

Answer 1

[Alan Stevens]

You need to change the size of the vectors etc appropriately. For example, for period = 0.2 you could have

T1 = 0.01;
t1 = 0:T1:0.199;
p1 = [ones(1,7) zeros(1,13)];
k1 = [0:10 -9:-1];
P1 = fft(p1)/20;
stem(k1,P1)

[Cheng]

what is p1 and k1 ? which one is the size of vector ?

[Alan Stevens]

They both have to be the same length. p1 defines the step. (and I think I should probably have defined k1 as

k1 = [0:6 -13:-1];

to more closely match the point at which the step occurs).

[Image Analyst]

Azmi, you keep forgetting to attach the m-file. We can't run an image, we can only run text that we can read into MATLAB.

[Cheng]

Image analyst, i used live editor . but the result is same as m-file tho ? or did i misunderstand something? can you try run it and show it to me

[Cheng]

Alan Stevens, as it goes from 0.2s to 5s, the graph become harder to read due to it space. any solution for this ? or just ignore it and write off my observation.

observation : as the period become more larger , the space between lines become more compact

[Alan Stevens]

It still looks ok at 0.5s:

T1 = 0.1;
t1 = 0:T1:49;
p1 = [ones(1,17) zeros(1,33)];
k1 = [0:17 -32:-1];
P1 = fft(p1)/50;
stem(k1,P1)

I suggest that for 5s you limit the plot domain using the axis command:

T1 = 0.1;
t1 = 0:T1:499;
p1 = [ones(1,167) zeros(1,333)];
k1 = [0:167 -332:-1];
P1 = fft(p1)/500;
stem(k1,P1)
axis([-50 50 -0.1 0.35]) 

This produces

[Cheng]

sorry i mean 5s not 0.5s . but thank you for your clarification . thank you very much