2
votes
2answers
96 views

Using FindFit for a non-trivial complex function [duplicate]

I have data set which I would like to fit to the function $\quad \quad f(r) = A\cos(kr - \pi/4 + \phi_1)\times\exp(i(-2\log(r) + \phi_2))$, where $k$ is a constant I know and $(A,\phi_1,\phi_2)$ are ...
-2
votes
1answer
61 views

Co-ordinates/ data marker in 3D plot

How to place the data marker or see the co-ordinates in below 3D plot and how to list all data points in this plot? ...
2
votes
1answer
114 views

Extract Transfer Matrix from TransferFunctionModel

I have a MIMO transfer function model, and I'd like to know how to perform arithmetic on this model. For instance, to see the difference between two systems' outputs for arbitrary inputs, I'd like to ...
2
votes
2answers
205 views
2
votes
3answers
72 views

An extra { when importing a file [closed]

I am trying to import data from a file. {k0,{a0,b0,c0},{e0,f0,g0}} {k1,{a1,b1,c1},{e1,f1,g1}} MyList = Import[file, "Data"]; But I get a list with an extra "{" ...
1
vote
1answer
158 views

DownValues when using Set and SetDelayed

It is known from several questions asked in SE that one of the basic differences between Set and SetDelayed is that the former ...
11
votes
5answers
585 views

Find all the possible ways of partitioning a list into a set of pairs of element

I have a list {x1,...,xN} where N is even, and I need to find all the possible ways to split it into pairs of elements, e.g. the ...
2
votes
1answer
230 views

Why does NDSolveValue giving crappy results?

I have been trying out mathematica 10 features, but sadly unable to use NDSolve for even simple PDE's. I am still wrestling with the problem of boundary conditions. The solution I get in the ...
1
vote
2answers
170 views

How to plot any 7 point shape in 2D i.e. star [closed]

I am new to Mathematica and I was wondering if anyone knew how to just plot simple shapes with at least 7 points minimum in 2D. What are the required steps I would need to start this? I believe I have ...
0
votes
1answer
103 views

Creating a residual histogram from discrete 3D data and function [closed]

Hi I have this data and my function on Mathematica: ...
6
votes
2answers
226 views

What's the difference between Interpolation[pts, Method -> Spline] and BSplineCurve?

Last month, I answered a question about spline interpolation,please see here Now I do the following operations ...
5
votes
2answers
209 views

Problems with ListPolarPlot

I want to plot the data that I got from measuring the angular dependency of the radiation intensity of a microwave emitter. My data: ...
8
votes
1answer
596 views

Is there any way to reveal a removable singularity in a plot? [duplicate]

Let's say we have a function $f(x)=\dfrac{2^x-2}{x-1}$. The graph of the function in Mathematica looks like this: The function in question is obviously not continuous at $x=1$, but that doesn't ...
7
votes
1answer
168 views

Optimal Binarize value for counting experiment

I am currently working on a physics experiment where I count particles. I have looked at and used a bit of code from the following sources: Cell counting from an image file and Count Elements in Image ...
2
votes
0answers
284 views

Open LabView's TDMS file?

How to open the National Instruments LabView TDMS files? Has anyone developed a library or code for easily importing these? National Instruments provide a DLL and specification for the format. There ...
3
votes
1answer
194 views

solving system of non-homogeneous advection equation using mathematica?

This question is followed up from this question How to solve a certain coupled first order PDE system Here I consider the non-homogeneous advection system \begin{equation} \displaystyle\left\{\...
4
votes
1answer
346 views

Using ParametricNDSolve and NMinimize to find accurate interplanetary trajectory arrival periapse radius

I have an interplanetary trajectory simulation that calculates the required velocity (using a Lambert solver) and escape angle for a spacecraft to travel from Earth to Mars. This model does not use a ...
4
votes
1answer
320 views

Can't run Bash scripts from within Mathematica 10.1

I am working on Debian 8 (Jessie) and Mathematica 10.1 (64-bit) Home Edition. I have created a script named curl_fetch.sh. It contains the line: ...
1
vote
1answer
104 views

Handle matrices and vectors with general dimension

I have a matrix of $n \times n$ dimension: $$ K - \omega^2 M = \begin{pmatrix} 2\omega_0^2 - \omega^2 & - \omega_0^2 & 0 & \cdots & 0 \\ - \omega_0^2 & 2\omega_0^2 - \omega^2 &...
0
votes
2answers
44 views

Equality of expressions containing complex numbers [closed]

I am using Mathematica to test the equivalence of symbolic expressions. I run into what appears to be a bug when I test the equivalence of expressions involving an imaginary number taken to a complex ...
4
votes
0answers
488 views

Precision and accuracy in NDSolve and NMinimize

I use NDSolve quite a lot and have noticed that setting values for AccuracyGoal and ...
7
votes
1answer
132 views

How to select a submatrix containing similar elements from a matrix? [closed]

( This question is related but does not ( fully ) answer my questions. - Finding the position of similar elements in a matrix ) I have not written code yet, I am in the design phase of code for the ...
1
vote
1answer
123 views

Discrete plots instead of parametric plots

I have a big iteration process and I want to look at the trajectories. Although if I consider ParametricPlot for this process, Mathematica connects points with lines. And for ...
14
votes
4answers
286 views

Association's Key[key] extraction different in V10.1/V10.2

V10.1: <|a -> 1|>[Key @ a] (* Missing["KeyAbsent", Key[a]]*) V10.0: <|a -> 1|>[Key @ a] (* 1 *) Bug or ...
6
votes
1answer
150 views

NMinimize Example from Wolfram Documentation Center

Here is the third example of NMinimize function from Wolfram Documentation Center at Possible Issues section. ...
11
votes
1answer
131 views

Preventing Keys from appearing in Query Output (+ the casting of Ascending/Descending operators)

One of the challenges of coming to grips with Query's on Association's and Datasets is ...
0
votes
0answers
42 views

Signage of eigenvector [duplicate]

I am comparing eigenvectors generated from mathematica to matllab. It seems signage of eigenvector generated from Mathematica is opposite from what is generated from matlab. Can anybody review and ...
0
votes
0answers
84 views

Clairaut's Theorem

Clairaut's Theorem: Suppose $f$ is defined on a disk D that contains the point $(a,b)$. If the functions $f_{xy}$ and $f_{yx}$ are both continuous on D, then $$f_{xy}(a,b)=f_{yx}(a,b).$$ Now, check ...
5
votes
3answers
286 views

Huge matrices crashes in Mathematica

I have a matrix of data ~(70,000x70,000). I am searching connection between these data points. I use euclidean distance for that purpose. If it is less than my threshold (that means they have ...
1
vote
1answer
123 views

How to reconstruct a surface given points {x, y, z} and the surface normals {nx, ny, nz} at these points

I have 3D points above a 2D regular grid. At those points I know the normal vector of the surface. I am looking a command or function in Mathematica, like ...
7
votes
1answer
130 views

Unevaluated @ {args} versus Unevaluated /@ {args}

Working my way through Robby Villegas's lovely notes on withholding evaluation, I almost got Polish Notation on my first try. Here is my final solution, which seems to work well enough: ...
3
votes
2answers
131 views

Meaning of D[f[x,y],x,y]

In calculus, we show our students: $$\frac{\partial^2 f}{\partial x\partial y} =\frac{\partial}{\partial x}\left(\frac{\partial f}{\partial y}\right) $$ Now, in Mathematica, which of the following ...
6
votes
2answers
239 views

NSolve erroneously gives no solution to a polynomial system

I have a polynomial system with three equations in three unknowns, the maximum degree is 26. Two equations are symmetric, i.e. eq1(x,y,z)=eq2(y,x,z). If I search ...
4
votes
1answer
492 views

Nonlinear PDE solver

I would like to solve the following nonlinear PDE: $$ \frac{\partial^2 \phi}{\partial x^2} - \frac{\partial^2 \phi}{\partial t^2} = \lambda |\phi|^2 \phi $$ I was trying: ...
0
votes
1answer
58 views

Mathematica Save Directory [closed]

Mathematica saves everything to Documents. I want it to save it into a folder Documents/Mathematica.
3
votes
2answers
84 views

Output matrix with common elements

Given lists of lists like a and b, I want to obtain an output like c. a = {{2, 1, 0}, {1, 2, 1}}; b = {{2, 2, 0}, { 2, 2, 1}}; c = {{2, 0, 0}, {0, 2, 1}} If ...
4
votes
1answer
151 views

Difficulty with total derivative

I am trying to introduce myself to the total derivative Dt in the documentation tutorial/TotalDerivatives. But I ran into what I think is a problem. There seems to be a serious problem in the ...
4
votes
2answers
170 views

Use of Ito's lemma in ItosLemma.m (or any other method in Mathematica)

This is a follow-up question on this question: Use of Ito's lemma in ItoProcess My problem is to find some method how to use Ito's lemma in Mathematica. As an example: How can I apply Ito's ...
7
votes
1answer
205 views

ParametricNDSolve[ ] and NMinimize[ ] in Combination

I have the following code that is used to simulate a spacecraft orbiting Mars, and uses ParametricNDSolve to vary the spacecraft's initial conditions using a parameter value ...
2
votes
1answer
112 views

Plot works while RevolutionPlot3D doesn't

I am trying to draw a surface of revolution recovered from a differential equation with a singularity. In the simplest case, the answer is a sphere. You can check by hand. I manage to draw 2 ...
4
votes
5answers
165 views

Using Through with SlotSequence

I have an expression consisting of a few pure functions added together like so: f+g+h I want to add the bodies of these functions together and make that a pure ...
0
votes
2answers
83 views

Summing complex numbers

Maybe it is a very stupid question but I am having trouble with summing complex numbers in Mathematica. I have q = l1 E^(2 π I t1) + l2 E^(2 π I t2) where ...
1
vote
2answers
240 views

How to change the scale of a ListContourPlot to logarithmic and combine it with a LogLinearPlot

My questions are: 1) how can I change the compressed scale to fine one like {y = 0.1, 1, 10}, {x = 0.01, 0.1, 1, 10, 100}. ...
3
votes
3answers
260 views

Partial derivatives of an implicit equation

Looking for an easy way to find partial derivatives of an implicit equation. For example: Find $\partial z/\partial x$ and $\partial z/\partial y$ if $z$ is defined implicitly as a function of $x$ ...
1
vote
0answers
60 views

How can I get the exact value of this infinite series? [duplicate]

I want to compute the exact value of this infinite series $$\sum_{n=1}^\infty\arcsin{\left(\dfrac{2}{\sqrt{n(n+1)}(\sqrt{n}+\sqrt{n-1})}\right)}$$ I tried to implement something like this ...
1
vote
1answer
274 views

How to solve a certain coupled first order PDE system

I would like to find the solution $(U,V)\equiv (U(x,t),V(x,t))$ of the following system. \begin{equation} \displaystyle\left\{\begin{array}{l} \frac{\partial U}{\partial t}+(a+b x)\frac{\partial U}{\...
0
votes
1answer
127 views

NDSolve precision for non-linear ODE with variable initial conditions

I am trying to numerically solve a non-linear ODE with variable initial conditions, specifically it is : $$ \partial_{t}R (r,t) ^2 + 2 R(r,t) \partial_{t} ^2 R(r,t) +r^2 k(r) = 0 $$ and my initial ...
5
votes
1answer
992 views

Plotting Tupper's self-referential formula using ArrayPlot

For those who are not familiar with Tupper's self-referential formula, here is the wiki link. My interest was to plot it. I tried the naive approach using ...
0
votes
1answer
66 views

Applying corresponding elements of a list to a list of functions

I found this post which applying a function to a list of functions and arguments. I thought I could change my code with a table to something more elegant. I am not wedded to the ...
2
votes
1answer
214 views

How to overplot Graphics on GeoGraphics? [duplicate]

I have a parametric plot and a GeoGraphic of the same size and I want to overplot them. Show doesn't seem to like to use both at the same time though it will display either. How can I put regular ...

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