# Uniform Interpolation/resample Question

3 views (last 30 days)
Tsuwei Tan on 21 Aug 2018
Commented: Rik on 22 Aug 2018
figure(1)
plot(exp_f2,exp_t2,'ro')
ylabel('Unifrom Time Step 2.5ms');xlabel('Hz');title('Mode 2 Exp data,fs=400Hz')
Here I have uniform time step 2.5ms on my y axis. But I need an uniform frequency step on my x axis like
f2_interp=linspace(exp_f2(1),exp_f2(end),400);
How can I interpolate or resample it? Thanks!

KSSV on 21 Aug 2018
% interpolation
ti=linspace(min(exp_t2),max(exp_t2),400);
yi = interp1(exp_t2,exp_f2,ti) ;
plot(yi,ti)

Rik on 22 Aug 2018
Sure, I can download that .mat file and load the variables, but that doesn't tell me what you want. I can't help you find a solution if you don't explain what you want. I've explained the three options. Pick one, or explain better what you want.
Tsuwei Tan on 22 Aug 2018
In your code, you make the exp_t2 which is already uniform step to be uniform again:
ti=linspace(min(exp_t2),max(exp_t2),400);
What I need is to make exp_f2 to be uniform:
f2=linspace(min(exp_f2),max(exp_f2),numel(exp_t2));
The output of "interp1" command doesn't have to be uniform, thanks!
Rik on 22 Aug 2018
Now I'm really confused. You want to make a variable uniform that is already uniform? And if you already have the code to do that, what is your question? And to what code are you referring to as "your code"? I haven't posted any code in this thread, only you and KSSV have.

R2018a

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