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Questions tagged [periodic-function]

The tag has no usage guidance.

0
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2answers
137 views

Plot on the surface of a Torus

I'm trying to plot a system with a variable (or field) $\theta(x,t)\in[-\pi,\pi]$ which is an angle at every position $x$. The positional argument $x$ itself is a periodic coordinate $x\in[-\pi,\pi]$. ...
0
votes
0answers
33 views

Finding the Period of a Complex Solution of NDSolve [closed]

I'm trying to solve a complex ODE with NDSolve and by plotting the solutions I can see that some of its solutions are periodic. I was wondering how can I find the period of these complex solutions? I ...
0
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1answer
48 views

Mathematica doesn't evaluate my Limit expression

I tried to evaluate the following limit: Limit[Sin[x]^n, n -> Infinity] However, Mathematica doesn't evaluate it, and just reprints the original problem: <...
2
votes
1answer
99 views

How to solve a PDE with periodic boundary conditions in one of the variables

I need to solve a PDE where one of the variables is an angle, so I need to know how to deal with periodic boundary conditions. As a warm up, I am trying to solve the Helmholtz equation in polar ...
-1
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1answer
103 views

Solving differential equation with periodic variable (poincare section)

I'm trying to make a Poincare section using the code here: ...
0
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1answer
95 views

How to find max and min values

Need to find max and min values like on pic. I am wondering how I could determine max and min values of oscillations ? How could I find these values: My code: ...
3
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1answer
60 views

How to efficiently implement periodic function to reuse computed values

Assume I have a function f = Function[t, VeryDifficultComputation] But I would like to exploit the fact that the function is periodic to "cache" computations ...
2
votes
1answer
164 views

How to make a square wave function with controllable period, phase and duty cycle that can work really fast?

I actually need two things: A square wave function that allows me to control its duty cycle, period and phase. It must work fast enough to be evaluated at least a million times per second. For the ...
1
vote
2answers
108 views

Using Nearest with periodic boundary conditions of a list

Take the list e = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} I want to get the nearest points but with a wraparound condition. So lets say I want to find the 5 nearest ...
1
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1answer
60 views

How to pad periodically a cube to be compatible with ListInterpolation?

Context I would like to define a periodic interpolation function on a cube. It seems mathematica's ListInterpolation and the option ...
5
votes
2answers
257 views

Periodic Orbits of the MacKay Map

For the MacKay (Henon action-angle transformation) Map (Mackay 1983): $x_{n+1}=q-\alpha x_n-x_n^2-y_n \\ y_{n+1}=x_n$ with $q, \alpha \in \mathbb{R}$ real parameters I would like to calculate the ...
0
votes
1answer
124 views

Using Fourier for periodicity and spike analysis

I am trying to look for significant peaks/spikes and periodic changes or fluctuations in about 60 time series of synthetic data. For example, in data1 below, there ...
1
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0answers
61 views

Definition of periodic conditions

I want to define some periodic conditions, for example, describing an ellipse in 2D with periods $p_1$ in $x_1$ direction and $p_2$ in $x_2$ direction. I am frying my brain trying to implement this, ...
3
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2answers
212 views

Using EventLocator to detect periodic solutions in NDSolve

I loop over some systems of DAEs with NDSolve; some solutions are periodic, some are not. When integrating with NDSolve, I ...
0
votes
1answer
67 views

Periodic function Iteration limit [closed]

I have two main issues. The first concerns Mathematica interpreting the same definition differently based on what I call the function, even though the name never occurs in any other part of the ...
1
vote
0answers
61 views

FunctionPeriod returns 0 if input trigonometric function have a real phase

I am using Mathematica 10, FunctionPeriod which is supposed to return period of a given function returns 0 if the input trigonometric function have a Real phase <...
2
votes
1answer
117 views

How to find period from graph

Code is: ...
1
vote
1answer
302 views

finding fourier coefficient of a parametric curve [closed]

There is a function in mathematica FourierCoefficient for finding fourier coefficients of a periodic function, but it requires the mathematical expression as input. ...
11
votes
2answers
409 views

Solution diverges in periodic PDE

Problem introduced in 11.0.1 and persisting through 11.3 Mathematica version 11 introduces PeriodicBoundaryCondition which is very useful in solving periodic PDE ...
1
vote
0answers
207 views

Periodic boundary condition trick

I'm plotting a curve on a compact space which is having periodic boundaries on the left and right parts. Currently, the code I'm using is working great, but I'm wondering if there's a simpler and ...
1
vote
1answer
484 views

How to find period of a discrete sequence?

For example, {1,2,3,4,5,6,7,8} has period 1, the base is {1} {1,2,4,5,7,8,10,11} has period 3, the base is {1,2} I ...
9
votes
2answers
574 views

How to locate the position of a periodic orbit

These are the equations of the dynamical system ...
3
votes
1answer
180 views

Computing planet conjunctions with 2D circular orbits still hard?

All methods I've seen for computing planetary/stellar conjuctions (when two planets or a planet and a star appear close together in the sky because their angular separation, as measured from Earth, ...
4
votes
3answers
259 views

Periodically tiling a function

I have a function which creates a hole of varying radius, depth and would like to tile it in x and y. ...
2
votes
1answer
502 views

Locating Periodic Orbits

Here is the code for the numerical integration of an orbit. First the module for the definition of the equations of motion. ...
5
votes
1answer
244 views

What's wrong in FunctionPeriod?

FunctionPeriod[Sin[16 Pi x/5 - Pi/8], x, Integers] 80 then I ListPlot the function: <...
6
votes
2answers
682 views

Integrating a periodic function

I have a periodic function ff: ff := Function[x, Piecewise[{{ff[x - 1], x >= 1}, {2 x, 0 <= x < 1}, {ff[x + 1], x < 0}}]] Plotting it works fine: <...
11
votes
4answers
618 views

Morphological Components with periodic boundary conditions

I would like to find the connected(with periodic boundary conditions) components in a large binary matrix. What I've tried, and it does a fair job is: ...
6
votes
1answer
131 views

Why do certain fractional values in TriangleWave not evaluate?

Bug introduced in 8.0 or earlier and persisting through 11.0.1 or later While answering another question I discovered that TriangleWave does not automatically ...
0
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1answer
2k views

How to plot the convolution of dirac delta series with a sine function [closed]

I am new to mathematica. I do the convolution of dirac delta :(DiracDelta(x-10)" with "sine(t),t=0-pi". How to plot the output ? Theoretically, the full wave should appear at the location of the ...
10
votes
5answers
5k views

How to create a rectangle wave (duty cycle $\ne$ 50 %)?

I'm trying to use phase-shifted SquareWave[] functions to create a rectangle wave: ...