I'm working with continuous-time (CT) and discrete-time (DT) signal and want to plot them in Matlab.

For CT, when I used the function linspace to create a vector of values and then use that to have a function (t1, x1 and t2, x2). I then plot the value of x() against the created t(). The graphs I got were different with different length of my vector generated by linspace and none of them seems correct. (The correct version is using the normal method* of creating vector (t3, x3)).

Code:

f=100;                     %Frequency
t1=linspace(0,1,100);      %From 0 to 1 in 100 steps
t2=linspace(0,1,300);      %From 0 to 1 in 300 steps
t3=0:0.001:1;              %From 0 to 1 and increment by 0,001

x1=cos(2*pi*f*t1);
x2=cos(2*pi*f*t2);
x3=cos(2*pi*f*t3);

subplot(3,1,1);
plot(t1,x1);
subplot(3,1,2);
plot(t2,x2);
subplot(3,1,3);
plot(t3,x3);

The same problem does not apply whether or not I use linspace or normal method* to create an array to plot magnitude and phase of a function.

Code:

w=linspace(-10*pi,10*pi,1000);
xa=(i*w)./(1+i*w);
figure(1);
subplot(2,1,1);plot(w,abs(xa));grid on;
subplot(2,1,2);plot(w,angle(xa));grid on;

If I generate w by normal method*, the graph still looks the same.

Can someone please explain!

Thanks.

I am trying to use linspace to create a time vector that is equal to length of the number of samples in an array. For example, I have a test with 30000 samples and each was taken 5ms in between As a result, first samples starts at 0, second at 5, third at 10th, and so on. I am trying to use linspace to accomplish this but running into problems. Here is what I am trying to do *test is the array with all the samples*

time = linspace(0, length(test), 5)

I am trying to create a vector that starts at zero and increments by 5 for each sample. All this does is create 5 times that are crazily spaced. I realize that the last variable actually just generate 5 number of points but thats not what I am trying to do as I want the step size to be 5. Any ideas? Thanks so much in advance!