## First order frequency response, no plot possible....

Hi guys,

I've had only a little experience with Maple, but I decided to use it for preliminary frequecy response calculations. The funny thing is, I have already the solution in some way, but I'm too stupid to get it working. I can't see the mistake, however, it should have something to do with the H_n(f) function and the other normalized functions.

NASA has published a nice paper which explains the calculations, however, they have used MathCAD. Anyway, I don't think this should be a problem. Here is the documentation: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070016024.pdf

The error message is for example for the H_n(f) function:

Warning, expecting only range variable f in expression H__n(f) to be plotted but found name H__n

Maple file: calculations.mw

## Frequency analysis for dsolve()...

Dear All,

I am working on ODEs and have obtained the plot for "variable vs time". I would like to know if it is possible and how to analyze those data in the frequency domain.ODEs.mw

Thank you.

Very kind wishes,

Wang Zhe

## letter frequency as function of word length...

Hello. I want to replicate the results of this table in Maple.

My "attempt" uses the inbuilt dictionary, but it will only find the words of length n, not the frequency of letters in each ....

word_length.mw

## How to reduce noise using a Fourier Transform on a...

Hello,

I've got a load of data that contains a lot of noise in the form of sinusoidal interference patterns. This is quite thick and it disturbes what I am trying to look at. I've uploaded a picture to represent what I am trying to show. I know I need a cut-off frequency I just don't know how to implement it. Thank you in advance for your help!

Gambia Man

## How to rescale axis?...

Hi all,

I have recentry constructed Fourier amplitude and Fouier Power graphs which are plotted against the frequency of the oscillations, like the picture below.

I would like to change the frequency scale along the x axis into a period scale in order to Fourier analyse future ODE systems in  terms of period rather than frequency.

But I unsure how to manipulate my code to do so.

Any help would be much apreciated, and the Maple file that I am using is attached.

Fourier_with_Period.mw

## Cumulative frequency in Maple?...

Hello I have this assignment. I will translate it (because it is not english)

This is the assignment: [IMG]http://i68.tinypic.com/2cgoby9.jpg[/IMG]

(if u cant click on the above link, then u can see it here http://tinypic.com/view.php?pic=2cgoby9&s=9)

So it says:

-------

In an examination of young pigs' birth weight 853 newborn pigs were weighted. The weighting is shown in the table down below.

[0,5-0,7] [0,7-0,9] [0,9-1,1] [1,1-1,3] [1,3-1,5] [1,5-1,7] [1,7-1,9] [1,9-2,1] [2,1-2,3] -> WEIGHT in kg

[26]            [43]       [102]       [145]        [171]      [196]     [119]       [42]          [9]      --> number of pigs

Draw a cumulative frequency curve of the weighting and determine the kvartils.

SO I usually do this in Maple, but this time I did a matrix but nothing happened.. I dont know how I should draw this curve? Help please.

[IMG]http://i68.tinypic.com/2cgoby9.jpg[/IMG]

## Histogram defaults...

Statistics:-Histogram by default choses the vertical axis such that the area under the histogram is 1 (or something like that). In my work, I invariably need to add "frequencyscale=absolute" to get the scale I need. Is there any way to make this the default? Typing this every time gets so old... I have been looking to something analogous to plots:-setoptions but that doesn't seem to exist for Statistics.

M.D.

## I want to obtain the formula of SINGULAR VALUE of ...

Dear.All

I'm a beginner of Maple 13.

In MATLAB, there is a command 'sigmaplot' which draw the 'SINGULAR VALUE OF SYSTEM H(jw)' over all frequency range.

I want to obtain the function of the 'sigmaplot' graph about frequency variable 'w'.

so I defined matrix A,B,C,D in Maple13.

and specify H like following

H:= Multiply(C,Multiply(Inversematrix(s*IdentityMatrix(8)-A),B))+D

--> It is to express H=C*((sI-A)^-1)*B+D that is the state-space matrix of frequency domain form.

and Maple 13 gave me a very long formular expressed by 's'.

Then I try to 'SingularValues' command

but there came up 'Error Message : Error. (in content/polynom) general case of floats not handled'

I couldn't resolve this problem....

Could you give some advice ?

## Solving ODE numerically...

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?  Non-unif.mw

## Create a count from a list?...

Hi,

r:=[3,3,3,3,4,4,4,3,3,3,3,3,3,3,3,2,4,3,1];

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!

Casper

## How can I turn Tally output into a list of lists?...

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":

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

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

## Deconstruct a waveform into its fundamental freque...

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