# All Questions

27 views

### Constructing a list of equations from a table with two indices [closed]

I need to make a list of equations like this {x + y == 0, 2x + y == 0, x + 2y == 0, 2x + 2y == 0} I tried ...
28 views

### “Why the Beep?” error when trying to save the document

I am new to Mathematica. I installed it yesterday, opened a tutorial video and after that tried to save my notebook but I got the following error message: Whenever I try to save my document I get ...
63 views

### Variable change

If I have the following Hamiltonian: ...
61 views

### NIntegrate vs. summation

I' m interesting in distributions of points on sphere, plane figures etc. Especially for small number of points: 1, 3, 7, ... It seems that good criterion for uniformity of distribution is some ...
31 views

### Linear system of stochastic differential equations

I want to solve linear system of differential equations of the following form $$X'[t] = M.X[t] + R.X[t]*\lambda[t]$$ where $X[t]$ is a vector of coefficients I want to have at time $t$, $M,R$ are ...
58 views

### Model without graphics

I have the next code: ...
51 views

### Export a Pyramid to VRML format

How do you export a Pyramid to vrml format in Mathematica ? I have been trying to do this the following way ...
59 views

### Slow application of Outer on a matrix

I have some performance issue with the calculation of a gaussian kernel applied to a not-that-large dataset. I'm not very good with performance tuning in Mma and I have the feeling this one could be ...
42 views

### Plot with two LabelStyle

I need to plot a graph with two different colors for the axis labels. Not working examples Plot[Sin[x],{x,0,2\[Pi]},Frame->True,LabelStyle->{{Red, Black}}] ...
144 views

### There is an issue with Manipulate in which it updates its argument twice in V10

I have asked this question before (here) and I thought that the issue is only when moving the Notebook window. It appears that Manipulate is working in weird manner. ...
25 views

### Operator Precedence [closed]

I want to know the operator precedence of this equation. I'm new. Please kindly elaborate your answer. sigma=x*y+k*H(r) mod q Your helps means a lot!
51 views

### Export Multiple Arrays Into a Single Worksheet with Column Headers

I'm importing financial data into Mathematica, creating column headers for each array and exporting to Excel. The code below accomplishes most of this, but it creates a different worksheet for each ...
43 views

### How to get an email address from a user [closed]

I need to obtain the email address of a user. Two problems arise: When I display an example email such as johndoe@domain.com, it displays with quotes which are very distracting to the user. If the ...
132 views

### Mysterious spikes in Plot3D

I am using Mathematica 9 and get these strange spikes when I plot the following simple function. I have seen a previous post about this but cannot figure out what is wrong with the following code. ...
34 views

### Errors when thickness is reduced solving 2D cylindrical heat conduction equation

I am trying to solve the heat conduction equation in cylindrical coordinates with a defined heat generation within the volume (a thin disk, with different heat flux BC top and bottom). The problem is ...
88 views

### How to plot on complex plane with Mandelbrot set

I essentially want to treat the Mandelbrot set plot as a normal plot so that I can plot arrows and points on top of it. This is what I want to do but it gives me an error: ...
74 views

### Simplifying $e^x>1$, is this a bug?

Simplify[Exp[x] > 1, x ∈ Reals] results in no simplification, although Reduce[Exp[x] > 1, x, Reals] correctly ...
80 views

### How to change the font color and size of tick labels by default

I've read Mike Honeychurch's answer here, and while it tells me how to change the font size on all of my plots, that size change affects (I think) all text on the plot. I would like to be able to make ...
46 views

### Are all of the numbers in my file legitimate hex numbers

I have about 10,000 hexadecimal numbers (32 digits each) in an excel file, in one column. I want to verify that all of them are indeed hexadecimal number and that no other characters are present. My ...
59 views

### Differential equations DSolve constant issue

After using DSolve to a set of differential equations, three constants arise. They are C[1], C[2] and C[21]. I have checked thoroughly that there are no C[3], C[4],....C[20]. It is quite mysterious to ...
43 views

### Strange Issue with RowBox

Can someone explain why this notebook [RANGEWORKING.nb] ...
60 views

### Output function control and manipulation for efficient computation

I have taken note of a similar post related to modifying function parameters. I tried to adapt Kuba's solution to this post but I can't get it to work. I will illustrate my problem using a similar ...
102 views

### Show plot legends for multiple curves in one plot [closed]

I have 5 curves, figure1a0, figure1a001, figure1a01, figure1ae01, and figure1ae001,. I display all these curves in one plot with Show. I want to give a label to ...
51 views

I recently set about to re-compile some old (2008-2009) applications that use MathLink in preparation for creating new, modified versions. Mathlink has been deprecated but WSTP seems like a fairly ...
649 views

### Is Mathematica ContourPlot function really so efficient?

I wanted to find the roots of the function $f(x,y)=\sin(3.2x)\sin(1.3y)-2.1 \sin(1.3x)\sin(3.2y)$. This is what the function looks like: ...
20 views

### Tricks to speeding up optimisation of a function involving a heavy integration

This is the code, and energycoeffs[] is the function that takes in a dxd matrix and spits out a scalar value. ...
24 views

### How to evaluate NMinimize inside a function

I want to define a function that returns a sum of differences of some points to a given function. To obtain these differences I would like to use NMinimize, but if I implement that straightforwardly, ...
24 views

### Why Table is not giving me the same sequence for eigenvalues of matrix

Let consider a matrix and evaluate the time dependent eigenvalues M[t_]:={{Sin[t],Cos[t]},{t,t*t}}; e1[t_]:= Eigenvalues[M[t]] Now If I evaluate ...
55 views

### Convolution of a piecewise function

I want to find the convolute the the functions in the Convolve command ...
40 views

### Error with using SortBy in a Map [closed]

I have a data set in the following format: SomeData = {{a, 1, 2}, {b, 2, 3}, {c, 3, 4}, {b, 1, 9}, {c, 1, 10}, {a, 2, 3}, {a, 3, 8}, {b, 3, 4}, {c, 2, 9}}; The ...
55 views

### Efficient image stacking

I have a list of lists of images that I would like to stack and create mean images for each list of images. Images are .jpg files 2592x1944 pixels large. Each list ...
37 views

### Vector Analysis in Version 8

Silly question. Why does Needs["VectorAnalysis`"] Grad[Sin[x^2 + y^2], {x, y}] give the error Coordinates::invalid: "{x,y} is not a valid coordinate system ...
43 views

### WorkingPrecision in LogLogPlot creates wrong plots

I seem to have found a bug with LogLogPlot in version 10. If I specify a working precision, the function produces total garbage. Here is a simple example. The first case, without WorkingPrecision ...
154 views

### Drawing a path which realises the diameter of the graph

So I enter a (0,1) adjacency matrix and I get the following graph: The diameter of this graph is 4. How can I ask that two vertices which realise this diameter be drawn with different filling ...
57 views

66 views

### How can I copy & paste cell styles?

In Mac's mail app the key shortcut "command + option + c" gives a copy selected text style and "cmd + opt + v" pastes the style. Is there a way to achieve this with cell styles? The keyboard part is ...
209 views

### Evaluating complicated trig without resorting to numerical methods

I have an angle theta given by Kx = (2/Sqrt[3]) ArcSin[Sqrt[3/10]]; Ky = (2/3) (ArcCos[(1/5) Sqrt[7/10]] - Pi); theta = Cos[ArcTan[Kx, Ky]]; This evaluates, by ...
17 views

### Error Using Mysql In Mathematica

I'm using Mathematica, and accessing mysql through mysql (Connector/J). When I try to update a field in my table using WHERE statement, all the rows get updated ...
90 views

### Context of localised (dynamic) symbols

When you localise a symbol with Module, the created unique symbol is usually in the current context. There seems to be an exception to this which has further ...
34 views

### Plotting Vectors in Mathematic at lat/long positions

I have some current data that I want to plot in Mathematica. The first two columns are the latitude and longitude respectively (longitudes are negative b/c it is west of the prime meridian and all ...
94 views

### Plot a table of lists

I want to make a point plot of a table with lists in it. Assume I have data like this: data={{1,2,3,4},{5,6},{1,5},{2,4}}; and now I want to make a point plot ...
44 views

### How to make Show work in Mathematica 10 Kernel

Wolfram Research says it no longer supports JavaGraphics in Mathmatica 10. This is very bad for people who prefer the Kernel to the FrontEnd. However, I am still able to get it to work. Show ...
43 views

### Table results within loops

I have the following code. ...
26 views

### Derivative inside a Series [closed]

I have a function defined by a sum, which I would like to differentiate. For example: ...
55 views

### How to filter my signal?

As you can see, my signal is superimposed by an other sinus which has a slightly longer frequency. I would like to filter this out. I think I can do the filtering process, but there is one step that I ...
46 views

### How to assign variables to selected roots of a polynomial equation? [closed]

I have a polynomial equation like the below, and I want to assign variables to the roots that are not pure imaginary. How I can do this? ...
1k views

### Can Mathematica's random number generation be improved?

Performance on Random Number generation is intolerable. Whenever you need many deviates from the same distribution but with different parameters it takes forever. Here is a thread on Poisson ...