13
votes
3answers
410 views

How to Import random elements of huge data files

I am calculating huge data files with an external program. I would like then to import the data into Mathematica for analysis. The files are 2 columns and up to many millions of rows. So for ...
11
votes
1answer
321 views

Triggering actions when a variable is set

Some built-in variables trigger actions when their values are changed: ...
1
vote
0answers
109 views

TableForm behavior change

In an older version NoteBook, I was able to specify some options for TableForm, which enabled the printing of an expression in a simple fashion: ...
2
votes
0answers
282 views

Runaway MathKernel!

I was running a simulation and everything went south (my fault, stupid coding error). So I quit the kernel. Everything was running very slowly, as if it were doing some kind of large calculation. ...
-1
votes
1answer
114 views

How can we suppress the asymptotic notation in Series? [closed]

Series expands a function, and also gives an idea of the asymptotic bounds of the function: Series[$\frac{1-x^3}{1-x}$] returns: $1 + x + x^2 + O(x)^5$ I'd like ...
1
vote
1answer
188 views

Partial row reduction of a matrix

I have an $m\times n$ matrix (presumably of full rank) with $m>n$, and I would like to row reduce it, but leave the last column unreduced; that is, I want to get output on the form $\pmatrix{ 1 ...
0
votes
0answers
191 views

Simultaneous Equation Solving Under Nonnegative and Bounding Conditions

I have nonlinear equations to solve parametrically; ...
0
votes
1answer
249 views

Can Mathematica check if two expressions give the same output for integer input?

Let me give the background for this question. I'm using WebAssign to assign homework problems, and WebAssign has a built-in mechanism which can grade problems using Mathematica commands. For ...
5
votes
4answers
595 views

How to find the index of a square matrix in Mathematica quickly?

Let $A$ be an $n\times n$ complex matrix. The smallest nonnegative integer $k$ such that $\mathrm{rank}(A^{k+1})=\mathrm{rank}(A^{k})$, is the index fo $A$ and denoted by $\mathrm{Ind}(A)$. I would ...
0
votes
1answer
216 views

How to display data in a Dynamic Pane?

How to display data in a Dynamic Pane without exponents? Some data: data = Range[1, 1000]; Slider data has to be added to data: ...
3
votes
1answer
245 views

Issue with ListDensityPlot when using logarithmic scale

I have got some frequency response data from a speaker measured with different incident angles between speaker and microphone taken in an anechoic chamber. The data can be found here. The whole ...
0
votes
1answer
164 views

Autocomplete not working on Mma9 on Linux

I started using Mathematica 9 on Ubuntu 12.10 and, sometimes, autocomplete doesn't work. The suggestions window shows up for just a fraction of second, and quickly disappears. Do you have any idea on ...
0
votes
2answers
102 views

How can I efficiently and uniformly sample the set of vertices a fixed edge-wise distance away from a chosen vertex?

I have a large graph $G$, which may be either directed or undirected. How would I use DepthFirstScan[] or BreadthFirstScan[] to ...
0
votes
2answers
914 views

large matrix eigenvalue problem

I need solve a very large complex matrix (not sparse and not symmetry) eigenvalue problem, e.g., 1e4*1e4 or even 1e6*1e6. How large dimensions of the matrix can Mathematica support? And, how about ...
0
votes
2answers
271 views

Problem with working precision

I have tried to resolve the problem of the following link How can I solve precision problem I can tell the problem described in that link shortly here, It's no mater how many precision is there after ...
3
votes
2answers
369 views

Animating the Lorenz Equations

I am trying to use the Animate command to vary a parameter of the Lorenz Equations in 3-D phase space and I'm not having much luck. The equations are: ...
4
votes
0answers
429 views

looking for a generalised Hough Transform function or a least a function to locate circles

I am looking for a generalised Hough Transform function or a least a function to locate circles (position of center and radius) in a image. There is the standard Hough line search function ...
-3
votes
1answer
149 views

How can I solve precision problem [duplicate]

I want to set 2 decimal places, whether it's real Number or anything.for that purpose I wrote the following function. ...
1
vote
1answer
229 views

CDF Player crashes on start-up Ubuntu 12.04 LTE

I'm not sure if this is the right place to ask this, if not, please redirect me. I am trying to get Mathematica's CDF player running on Ubuntu 12.04 LTE (Precise Pangolin). This should be fairly ...
7
votes
1answer
148 views

ClearAll just for current notebook

So in my search to fine tune Mathematica to what works for me, I found a nice setting that helps separate variable declaration between notebooks. Under Global Preferences, searching for CellContext ...
2
votes
2answers
99 views

Rising Recursion Relationships

Lets say I want to compute the following function in mathematica: $G[n,k]=G[n+1,k-1] + G[n+2,k-2]$ where I know that $G[n,0]=n$ and $G[n,1]=n^2$. So, for example, $G[3,2]=G[4,1]+G[5,0]=4^2+5$ or, ...
0
votes
1answer
94 views

Function giving negative value when it should be positive [closed]

I am trying to evaluate $$\displaystyle J=A\sum_{k=0}^{n-2}(-1)^k{n-2 \choose k}B^{n-2-k}\left(\frac{C_1}{k+n}-\frac{C_2}{k+n+1}+\frac{C_3}{k+n+2}-\frac{2}{k+n+3}\right)$$ in Mathematica as a function ...
0
votes
2answers
306 views

Draw network graph and get the coordinates of each node

I would like to draw an undirected graph by specifying the nodes and the edges among them. This is currently done by, for example: ...
0
votes
1answer
128 views

How can I extract coordinates of the nodes of my graph?

I have this output for my graph. ...
11
votes
2answers
389 views

Diagonal Tick Marks

I would like to draw diagonal tick marks around a plot, and simultaneously rotate the tick labels as well. I've mocked up what this would look like: Is there an easy way to do this in Mathematica? ...
12
votes
1answer
232 views

ToNumberField won't recognize Root as an explicit algebraic number

In Mathematica 9.0.1, it appears that ToNumberField will not always recognize a Root object as an explicit algebraic number. ...
1
vote
0answers
129 views

Is there a keyboard shortcut for Centered Math Cell?

I've been typesetting in mathematica and would like to know if it is possible to use a keyboard shortcut to place a centered math cell or equation symbol aligned math cell in my document without ...
2
votes
3answers
279 views

Drawing a complete graph of an ego network

I have an ego network (a network of a person (ego) and his friends). It is drawn with the ego at the center surrounded by the friends. It might be possible that all the friends are connected to each ...
2
votes
0answers
152 views

Fast calculation of commute distances on large graphs (i.e. fast computation of the pseudo-inverse of a large Laplacian / Kirchhoff matrix)

I have a large, locally connected and undirected graph $G$ with $\approx 10^4$ vertices and $\approx 10^5$ to $\approx 10^6$ edges. Moreover I can bound the maximum vertex degree as $Q_{max}$. I ...
6
votes
4answers
658 views

data visualization on a lattice grid

Is it possible to visualize an array whose elements are angles as actual angles on a lattice grid? E.g., say, if the input is: ...
0
votes
0answers
40 views

How to use an arbitrary closed region to extract an image region of interest [duplicate]

I am working on images and I need to be able to extract into a list all the image points that fall within a closed region, such as gotten from using "get coordinates". I can extract the points from ...
0
votes
1answer
144 views

Error messages when using NInverseFourierTransform

I have two functions that I need to inverse Fourier transform and I was trying to get Mathematica to help me. I tried simply using theInverseFourierTransform ...
0
votes
2answers
476 views

Fast Autocorrelation Computation

I want to compute the Autocorrelation Function (ACF) of a data table with $10^6$ entries. I know that there is a built-in function in Mathematica for that, but because I do not know how exactly it is ...
0
votes
1answer
184 views

solution of differential equation

I have the following code that gives you a phase portrait of a 2d system and I can't understand what means the 3rd and 4th line (sol1 and sol2). ...
2
votes
0answers
111 views

Teaching Plan for High School Students [duplicate]

I would like to eventually teach Mathematica to my future high school students. In high school, there are many students who haven't taken a computer science class yet. I know Mathematica can get ...
0
votes
1answer
69 views

Substituting Data from File

I have sets of Diff. Eq. that I'd like to solve symbolically, then substitute in numerical values for some of the symbols. I'd like to store the value for each symbol in a file, e.g., an excel ...
0
votes
1answer
91 views

Define variable relationships and dynamically update variables

I would like to define a relationship between 3 variables first and then later when I have filled two of the variables with a number, I would like to extract the value of the last value. For example: ...
4
votes
2answers
301 views

ComplexExpand absolute squared

ComplexExpand[Abs[a + b I]] Gives $\sqrt{a^2 + b^2 }$ ComplexExpand[Abs[a + b I]^2] On the other hand gives Abs[a ...
0
votes
2answers
139 views

Convert *.txt file

I would like to Import and Convert a *.txt file which looks like: https://docs.google.com/file/d/0Bw-308nJcF01Yl92RURCLUg4VzQ/edit?usp=sharing and turn it into a Matrix which I can use to make ...
10
votes
1answer
487 views

Mathematica Functions from VBA

I'm trying to call Mathematica functions from VBA (Excel) using .NETLink without success. (Yes, I know Mathematica Link for Excel exists. And yes, I know the proper thing to do is buy it. However, ...
1
vote
1answer
230 views

Additional label on axis - 2D plot

I am finding a local maximum of a curve and I want to make the plot easier to read. I added a point to where the maximum is but I would also like to: 1) add a tick with text below it where the x ...
1
vote
2answers
727 views

How does one specify Neumann conditions for NDSolve?

I have a series of functions defined in my notebook, and then want to use this to solve a diffusion-reaction type equation. At the moment, something like this works: ...
5
votes
3answers
943 views

How to speed up the plot of NIntegrate?

Here is a toy example: f[t_] := NIntegrate[Sin[x], {x, 0, t}]; Plot[f[t], {t, 0, 10}] // Timing Even such a simple example will take 2.8 seconds on my computer. ...
7
votes
0answers
270 views

Caching of Graph Graphics

In this answer, Simon Woods concludes that when you display an expression with head graph more than once, something is getting stored somewhere. I looked into it too and found out this only happens if ...
1
vote
1answer
122 views

How can I import sound from within a Manipulate expression?

I want to import sound from a file, record, and import sound. ...
2
votes
2answers
295 views

ColorFunction based on data

I have a list of numbers, and I would like to plot them using ArrayPlot (which is easy, usually :)). I would like to be able to color the elements of the plot based on the average of the list: one ...
0
votes
1answer
97 views

How to delete duplicate solutions of this system of equations?

I want to find vertices (has integer coordinates) of the triangle $ABC$ with the centorid is $G(1,1)$ and orthocenter is $H(3,3)$. I tried ...
4
votes
3answers
593 views

Compute the rank of a matrix with variable entries

Say I have a matrix like $$ M=\left( \begin{array}{c c c} x & xz & w-2x \\ wz^3 & xy & z \\ y^2-z^3 & x+w & z+x^5 \end{array} \right) $$ is it possible to ask Mathematica ...
16
votes
4answers
3k views

Finding Local Minima / Maxima in Noisy Data

I'm trying to find local minima / maxima in noisy data, consisting of data values taken at certain time intervals. Ideally, the function should take a pair of lists (one containing time values and one ...
6
votes
1answer
505 views

Problem with SerialIO package and Lego NXT

I'm following a guide from The Mathematica Journal that describes how to use Mathematica with the Lego Mindstorms NXT but have some trouble getting started and got stuck with the SerialIO package. I ...

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