# All Questions

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### Mathematica on Linux Ubuntu: antialiasing issue

I'm working on a webMathematica application using a linux server (Ubuntu 12.0.4 LTS) with Xtightvnc. Even though the system administrator has done all the possible to set the anti-alising features, we ...
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### SIR Model with Dynamic module

I am having trouble with generating a parametric plot with the following code: ...
26 views

### How can I convert a Piecewise into a nested If?

For later conversion into a programming language where if is the only conditional construct, I would like to convert a Piecewise ...
22 views

### Solve For X inside arc-cos function (with division) [on hold]

Very basic but I've been stuck for more than 12 hours trying to solver this equation 20=360/(arccos(X/3200)*2) Can anyone solve X? and explain what exactly you ...
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### RecurrenceTable [on hold]

I got an error saying ...
33 views

### How can I import a pickled file?

I have a file generated from a python script that dumped a dataset into a pickle "data.pickle", I am at a loss as to how to Import the file, since "PICKLE" is not ...
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### Assigning some results after a solve procedure to the coefficients of a matrix

I have a matrix M[3,3]. After a solve procedure, I obtained these results. {{M[1, 2] -> Cos[ψ[t]], M[1, 3] -> 0, M[2, 3] -> 0, Cos[θ[t]] -> M[3, 1], M[3, 2] -> 0, M[3, 3] -> 1, M[2, 1] -> ...
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### Extract the divergent/bounded part of a certain expression

Consider I have a power series which is function of $x$. A part of this expression is bounded when $x->\infty$, some remainder is on the other hand divergent when $x$ goes to infinity. What is the ...
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### Extract a part of Series

If I have the output of Series, in terms of powers of my variable $x$, what is the quickest way to extract a part of the series, say for example the terms from $x^2$ to $x^5$, excluding those with ...
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### Extract a term of Series output

Say I have the output of series, with all the coefficients of the different powers of my variable $x$. What is the quickest way of extracting the coefficient of the $n$-th power of $x$?
36 views

### Interpolating a non-continuous set of points

I'm trying to create a pure function that I can feed into OutputResponse[ ] as the input u[t]. In order to do this, I've written code to create a square wave pulse train in the form of a collection of ...
29 views

### How to do n-fold cross validation with Classify?

Other machine learning libraries have utilities to generate indices that can be used to generate dataset splits according to different cross validation strategies. How do I tell ...
29 views

### How to use If to compare a function

I'm trying to write a Manipulate demonstration where you can select one of a number of functions. At one point I need to test if the function chosen is a particular one, and it seems to work if the ...
28 views

### Calculating the rank of an abstract matrix

I'm trying to compute the rank of a 4x4 matrix with 4 parameters and 2 variables. I tried to calculate its rank under some assumptions on those conditions and I kept getting rank 4. So I did an ...
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### Somebody imported .mdt files (3d graphics) in Mathematica?

Hello maybe someone did or import this format in math for subsequent presentation in 3D
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### Generating a C/C++ Code with a Non-Linear Vector Function [on hold]

In Mathematica, I have a vector RES = {f1,f2,f3, ..., f7} where f1 thru f7 are non-linear functions of my degrees of freedom: a1 thru a7. I know that I can use: ...
29 views

### Estimating inherent parameters for projectile under influence of wind in 3D based on measured data

The goal of this is to be able to estimate the drag constant $k$ and mass $m$ for a projectile based on measured landing coordinates $P$, start speed $v$ and launch angles $\varphi$ and $\theta$ ...
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### How to Map a function with HoldAll attribute

First of all, I'm not sure about the title of this question, so please correct me if there is any title more sensible than mine. The problem is the following: I have a function f that checks if a ...
28 views

### Mathematica not seeing my environment/system variables

I'm trying to access my environment variables in Mathematica, but I get a Failed result every time. For example: $echo$USER jlconlin but in Mathematica I do: ...
43 views

### Infinite Sum with exclusion

From another question I tried to implement something like: Sum[r^(1 - l[n]) DD[n], {n, Complement[Range[1, Infinity], {4}]}] but this does not work because ...
196 views

### Median household income for each county in Maryland

I found that Wolfram|Alpha knows the median household income for every county in the US. I wanted to get a list of all counties in Maryland, and the median income in each county. The only way I could ...
29 views

### Truncate a sum in a 'smart' way

Consider a series like this: $$\sum_{n=1}^{\infty} (c_n r^{2-n/2}+d_n r^{-n/2})$$ Sum[c[n]r^(2-n/2)+d[n]r^(-n/2),{n,Infinity}] I want, now, to keep only the ...
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### Launching 49+ local kernels fails in 10.0.2

I do large-ish parallel computations in Mathematica on quad socket 16 core nodes (64 physical cores). In version 8.x, LaunchKernels[64] works reliably. In version 10.0.2, LaunchKernels[48] works ...
13 views

### html embedded cdf does not print

Upon exporting an nb file to an embedded CDF for viewing in an html file, no print image is displayed when I attempt to print the web page. Given that the CDF Web Development Wizard also produces a ...
63 views

### How to solve a heat flow equation [on hold]

I am a beginner in Mathematica. I was wondering if anyone could give me some pointers as to how to solve following type of equations. During a particular time interval, ...
103 views

I am familiar with regular expressions in other languages (e.g., Perl, Python, ViM), but the Mathematica StringExpression is baffling me. I'd like to match strings ...
40 views

### Don't understand why my Do-loop is misbehaving [on hold]

I have a 2D array, initialized by array = ConstantArray[0, {10, 1000}] and I want to assign numerical values to ...
52 views

### several plots at once

I have several files what i would like to plot at once, they are .dat files and they have names as a numerical sequence from 1 to 4 (they are about a hundred but for the example 4 are ok) so i use ...
34 views

### Series identity with binomial coefficients [duplicate]

I have this apparently simple equation: ...
82 views

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### Unknown number of variables in a logical statement [on hold]

Resolve[ ForAll[{i, y[i]}, Implies[i >= 0 && i < 3 && Implies[i < 3, y[i] > 0], Sum[y[i], {i, 0, 2}]>0]]] returns ...
29 views

### Selecting elements from a list [duplicate]

I have the following array of numbers: a = {{0, 2, 5}, {3, 5, 1}, {4, 0, 5}, {8, 3, 4}, {0, 8, 6}}; then I make a list of the first row with ...
54 views

### CDF of experimental data

Here is data.csv: ...
50 views

### Random numbers genereated from sum of multiple Gaussian distributions [on hold]

Does anyone know if it's possible using Mathematica 10 to generate random numbers from a dsitribution that is a sum of Gaussian distributions? Or if there are packages that are available that is ...
46 views

### Improve performance of processing transactions in a large file

I want to work with a table which has 296,705 transactionslines and 172,147 transactions. ...
41 views

### Importing 2D array of image

Suppose images = {{1.jpg,2.jpg},{3.jpg,4.jpg}} Now I try to import all of them in level 2, Map[Import[#],image,{2}] Why Mathematica says it is invalid file? (error= Import::chtype)
32 views

### NDSolve emitting error message NDSolve::ndnum [on hold]

I am trying to solve this system equn1 = ψ'[x] == - Elec[x] equn2 = Elec'[x] == - ((di/ a)^2)[(Exp[ψ[x]] - (x/(xoi*Sqrt[-ψ[x]])))] For that I am using ...
20 views

### Finding a function to map one set of numbers to another on a curved line? [on hold]

I have a set of random numbers and I have to generate a new set of random numbers from these numbers. So if x represents my original number then the new number would be y. Here is what I know so far ...
15 views

### Independence Number of Graphs [on hold]

Suppose $\alpha(G)\leq\alpha(H)$ where $G$ and $H$ are graphs, and $\alpha(.)$ is the independence number of graph. Is the following statement true? $\alpha(G\boxtimes G) \leq \alpha(H\boxtimes H)$ ...
37 views

Thread[f[{a, b, c}, 0]] (* {f[a,0],f[b,0],f[c,0]} *) Thread[f[{a, b, c}, pp[0]]] (* {f[a,pp[0]],f[b,pp[0]],f[c,pp[0]]} *) Howerver, the head of pp ...
39 views

### Nonlinear matrix equation solving in Mathematica

is it possible to solve below equation in Mathematica? A.X+B.Exp[X]==C A, B are square ...
76 views

### Finding minimum of a list of pairs

Sometimes I need to find the Min of a list, whose elements are lists (say of two elements, a pair). Given that Min does not have the option to indicate a sorting function like Sort, I elaborated the ...
41 views

### Table yields unexpected result [duplicate]

I evaluated Table[#[[i]] &, {i, 1, 5}] and got ...
26 views

### How to implement Wolfram|Alpha like interface in Mathematica? [on hold]

I want to write a good-looking function to calculate something. I see that WolframAlpha["gravitational acceleration"] Returns a calculation field looks good, ...
47 views

### Combine 3D plots into one with Manipulate and different region plots

The following script generates two plots in a row, both of them controlled by Manipulate. I would like to combine them together in one. The problem I don't know how to solve is that the plotting ...
28 views

### Changing Function Domain of Fourier Series

If I write FourierSinSeries[x, x, 10] Mathematica will output the first 10 terms of the Fourier Sine Series f(x) = x defined for 0 < x < Pi. How do I output the the Fourier Sine Series for ...
32 views

### How to Clear derivative definitions?

I can't find a Clear or ClearAll command that gets rid of Derivative definitions I created. this code: ...
23 views

### FindRoot[rhs==lhs, {x,x1,x2}] Vs FindRoot[rhs==lhs,{x,x1}]

What is the difference between these two commands: FindRoot[rhs==lhs, {x,x1,x2}] and FindRoot[rhs==lhs,{x,x1}] They give ...