# All Questions

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### How to check empty tables using SQL Select or Execute?

If[SQLExecute[con, "Select * from TABLE"] == "{}", Print["TRUE"], Print["FALSE"]] I need to know the way, if the TABLE is empty or not
1k views

### How to speed up my Project Euler code

The evaluation speed of Mathematica often depresses me. It did it again when I wrote a code to solve a Project Euler problem. https://projecteuler.net/problem=206 Here's my code: ...
178 views

### Deployment to the Cloud not working

I am really trying to get my head around Cloud Deployment and Programming cloud, and the more I use it, the more I think it is a fantastic product. At least in principle. I successfully deployed a ...
167 views

### Extract data from NDSolveValue result

Okay this is a very newbie question. I have coded a sample problem that solves the heat diffusion equation on an annulus. Here's what I have: ...
200 views

### Mathieu function periodicity problem

According to the documentation, the Mathieu characteristic function generates parameter a: The characteristic value Subscript[a, r] gives the value of the parameter a in y′′+(a-2q cos(2z))y=0 ...
73 views

### Select a Placeholder in a Notebook?

How might I select the 1st Placeholder in a Notebook? SelectionMove Has no option. ...
135 views

### Solving a system of difference equations in an exponential steady-state growth setting

I have a system of difference equations in an exponential steady-state balanced growth setting; all variables grow at the same steady-state rate, say, $g$. I use the notations as follows: Variable $X$ ...
293 views

### Eliminate 3 Variable from 4 Equations

I am trying to use Mathematica to Eliminate 3 following variable from 4 equations. Any clue or link to similar solved problem is highly appreciated: ...
182 views

### How to find a recurrence relation for a sequence?

I have a sequence given by an explicit formula for n-th term: ...
134 views

### Keyboard Shortcut several Keys

I would like to set up a system (or define a keyboard shortcut) so when you type the following sum I have the following print at the current selection. ...
341 views

### Coloring edges of a graph according to their weight?

What's the simplest way to plot a graph with weighted edges, such that the color of the edge corresponds to the weight of the edge?
844 views

### How can I construct and visualize a hypergraph?

A hypergraph is a generalization of a graph, in which an edge can connect more than two vertices. Thus you can think of an edge in an hypergraph as a subset of nodes. Since version 8, Mathematica has ...
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### Behavior of Commonest when there is an even split between the elements of the list it is given

How can I alter Commonest so that, when I give it an input of four zeroes and ones such as $\{0,1,1,0\}$, which has an even split in its elements, it returns the ...
299 views

### interpolating function over dates

I've got a bunch of readings at various dates and times. I'd like to be able to interpolate and then integrate over, say days. I can do this by converting my date/time to ...
164 views

### How to Nest a Function with three Arguments?

I have two functions with three arguments $f_x(a,b,t)$ and $f_y(a,b,t)$. And i need a nesting like this ...
83 views

### Problem with FrameLabel in the ErrorListPlot function

I've been trying to print information on the axes of a graphic. I'm doing that by the option FrameLabel in the ErrorListPlot ...
237 views

### How to build a game board [duplicate]

I have - rather lazily - constructed a chessboard like this: ...
152 views

### What should I do if the geographical map provided by Mathematica doesn't show some rivulets?

I have a list of geographical coordinates(maybe the coordinates are not that accurate, but the problem is not that vital): ...
566 views

### FEM: Nicer Element Shape for Spherical Region

I'm trying to generate a mesh for later use in the Finite Element Method of the DSolve command. It is basically a parallelepiped with a spherical indentation. I'm ...
52 views

### Difference in output from R's mvtnorm and Mathematica/Java

Let a=$\mathcal{N}(6.532056,0.06532056)$,b~$\mathcal{N}(8.390961,0.08390961)$ and c~$\mathcal{N}(8.736566,0.08736566)$. We use $\mathcal{N}(\mu,\sigma^2)$ notation unless specified otherwise. We ...
68 views

### Inactive derivative: extract constants

I have a problem with an unevaluated derivative. In the example code below, i need the integration wrt to y be evaluated, while the differentation wrt x needs to stay unevaluated. I see the point that ...
289 views

### Segmentation of sunspots

I recently went for a walk with my camera and snapped a few pictures of the sun. The pictures didn't turn out too well, but this was to be expected without a telescope. I thought it might be a nice ...
176 views

### Dynamic ListLinePlot

I have a list of lists looking like this: {{{x1, y1}, {x2, y2}}, {x1, y1},...}}. Furthermore I have defined a legend, which is taken from the filenames. Now I want ...