# How can i write the frequency vector for frequency range 5-400 hz using 50 frequncy points

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Lisa Justin on 13 Jul 2012
How can i write the frequency vector for frequency range 5-400 hz using 50 frequncy points

Wayne King on 13 Jul 2012
Hi Lisa, you cannot have 50 frequencies in 30 elements. Obviously whatever Q is here (is it a power spectral density estimate?) is an estimate at only 30 frequency points.
You can space your frequency vector to cover 5 to 400 Hz with fifty points and then select a subset of those 50 so that you can plot(f,Q)
freq = linspace(5,400,50);
% just making up some junk data to plot
Q = abs(randn(30,1));
plot(freq(1:30),Q)

Ryan on 13 Jul 2012
Edited: Ryan on 13 Jul 2012
FrequencyVector = linspace(5,400,50); %linspace(min,max,# of points)
Lisa Justin on 13 Jul 2012
f=linspace(5,400,50);
plot(f,Q)
it won't work
Q has a length of 30x1
and f has a length of 1x50
How can i make f 1x30 and still ranging from 5-400 and 50 frequency points
Ryan on 13 Jul 2012
See Wayne King's answer. These type of details should be included in the original question to provide the best answer possible.