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Hi. I am trying to identify mode shapes (phi(x)) and natural frequencies  of non-uniform euler-bernoulli beam. There are number of numerical methods to solve ODE with certain boundary conditions (i.e. Runge Kutta method). Problem is that I am newbie here. I am interested in particularly first vibration mode and its frequency. Is there anyone acquainted with it and would be able to help me?





What's the shortest way to create a frequency table from it?


Ie, tells me elements are 1,2,3,4

the corresponding counts are: 1,1,13 and 4

and then if it can return the number with highest counts: 3

Many thanks!


I am presently using Tally to read through a list of numbers to try and calculate their frequency, I end up with a list as follows:

frequency := [1 = 6, 2 = 7, 3 = 91, 4 = 10], etc.

Now, I've been given a function that should turn this function into a "list of lists":

list_of_lists := n -> [ op(n)[1],  op(n)[2] ]

As can be expected from looking at this function, it only returns the first two elements from the original list


I have a sample waveform of an air conditioner and want to see if any low frequencies (10 Hz which is harmful to human health) exist in the wave.  How can I do that?


Granted the frequencies picked up in the recorded file depend on the quality of the recording and the recorder and lower frequencies may not have been picked up. 


I've looked at

The quantity ω(x):= limsup_T->+infinity Pi/T*ν(x,T) is said to be the frequency of a function x:[0,infinity)->R,
where ν(x,T) equals the number of zeros (taking into account  the multiplicities) of the function x on the interval [0,T].
a) To estimate from above the frequency of any non-zero solution of the ODE diff(x(t),t$2011)+x(t)=0.
b) To find the frequency of the function x(t):=sin(t)+sin(Pi*t).


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