# All Questions

196 views

### How does one unpack the contents of a list while using rules to substitute values for each variable?

My intention is having a large collection of variables (symbols to be more specific) in a list and substituting all the variables at once with a value using rule instead of going through each one, one ...
185 views

### Fraction shortcut not working, giving strange spacing character on german keyboard

So usually when you want to enter a fraction in Mathematica, you can do so by pressing "Ctrl+/". If you are on laptop with a german keyboard however, you will have to press "Ctrl+Shift+/" since you ...
128 views

### SQLInsert'ing Null into a table (not SQLite)

Is it possible to insert Null values using DatabaseLink, without formatting the query string manually? Hans found (below) that this works for SQLite, so it appears ...
98 views

I have been running a function in Mathematica 10 with the command, DeleteDuplicatesBy. The function was working great until one day I started to get an error with ...
148 views

### Estimate parameters of AR1 process

I am trying to estimate the parameters of a series $Z_t=W_t^\beta$, where W_t follows an AR1 process with mean 2, $\rho=0.9$ and $\sigma=0.1$: $W_t = \rho W_{t-1} + (1-\rho) \bar{W} + \epsilon_t$ ...
107 views

### Package functions not loaded after successful Get (<<) [closed]

I have the following package: ...
173 views

### Why does FindFit work and NonlinearModelFit does not?

I have a somewhat complicated function that I have defined. ...
70 views

### NDSolve does not satisfy initial conditions

For the problem I'm facing, I have three coupled diff eqns that I'm trying to solve ...
253 views

### How to solve a pair of coupled 2nd order equations using shooting method

I have a pair of equations for x[t] and y[t]. Both are 2nd order and they are coupled. Now say that I know the following ...
123 views

### Can't get rid of vertical background color

I am trying to use GraphicsGrid, the background option is set to white, as well as for the separate graphs. But there are still grey stripes. What is the reason for ...
68 views

### Equations in a quadratic field

I would like to solve a system of equations in a quadratic field, meaning that each variable $x$ of my system can be written $a + b \sqrt{d}$, where $d$ is a fixed value. Suppose for example that I ...
97 views

I have a pretty ferocious integral to solve, and since it doesn't seem I'll be able to do much analytically, I've taken to Mathematica to get some information. Mainly, I want to see if there are any ...
101 views

### Help plot with horizontal filling

I want to plot a graph that looks like the following, where the blue curve is $y=x^2$ and the red lines are $y=8x-12$ and $y=-8x+20$. The filling is applied horizontally from the lines to the edge of ...
61 views

### Can list interpolation be made listable? [closed]

I have 8 sets of 2D-data that I want to each interpolate with ListInterpolate, because it is a very efficient command. The complete data are therefore in a 3D table....
117 views

### AxesLabel style like in FrameLabel [closed]

I would like to use ListPlot without Frame. But AxesLabel produces y-label above the y-axis ...
285 views

### Inverse of Interpreter[“Color”]: Convert a RGBColor to a natural language color name

What is the best way to create the inverse function of Interpreter["Color"]? That function takes a natural language color name like ...
535 views

### How to plot an ellipsoid from an implicit equation [duplicate]

I need a way to plot a generic ellipsoid given the following implicit equation. Can someone help me? $$\frac{x^2}{a^2}+\frac{y^2}{b^2}+\frac{z^2}{c^2}=1$$
63 views

### How do I center an item in a Grid?

I was trying to use Grid to align different plots, two on the first row, and only one in the second row, so I have something like this (where a,b and c are plots): ...
166 views

### Using Padding with Text and Style

Suppose that I use: Text[Style["(1, 0, 0)", 12, Background -> White], {1, 1, 0}] How can I put a few points of padding around the text? Thanks to Jens: ...
86 views

### Using Simplify to perform substitutions [closed]

I have a matrix element $k_x$ and I want to substitute it as $-i\kappa$, I tried ...
79 views

### How to increase font size in front-end UI Menus [closed]

Is it possible to increase the font size in the notebook GUI's menus, messages window, help windows, etc?
41 views

### Boundary condition [duplicate]

I'm having the following issue that can not find a solution , by using this boundary condition v[0, t] == u[1, t] that Mathematica does not understand, someone ...
48 views

### Construct a button to start a routine [duplicate]

When executing Button ["Print" Print[1]] you get a button that, if pressed, prints to the screen 1. What I would like to have is ...
61 views

I have a directed graph with this Edgelist defined as follow: ...
172 views

### Get the creation time of a file

Windows is able to tell me when (date & time) a file in the file system was created or altered. Is it possible to get such information in Mathematica, e.g., get the creation time of a text file ...
52 views

### How to enter options when using an input palette

Integrate[1/(x^2 + y^2 + z^2)^(5/2), {x, 0, b}, {y, 0, l}, GenerateConditions -> False] We can type in the above expression easily. But if someone new to ...
193 views

### Improving NDSolve computation speed for 3D stationary PDE

Continuing my last question, I am trying to solve 3D Schrodinger equation (with mass equals to 1) and with no potential (I will add a potential later). The analytical solution for this equation is ...
86 views

### creating a stacked function that returns the multi varibles

I'm a beginner in Mathematica with little programming background but I'm determined to learn this. I'm trying to make a function that calculates two variables r2 &...
147 views

### Equal flow boundary conditions

I'm having the following issue that can not find a solution , by using this boundary condition v[0, t] == u[1, t] that Mathematica does not understand, someone ...
124 views

152 views

### What am I doing wrong when using Solve ( Wolfram Alpha)

It is not because we do not interpreted correctly WolframAlpha["Solve[64(!(*FractionBox[(x - *SqrtBox[(*SuperscriptBox[(x), \ (2)] - 1)]), (x + 1)]) !(*SuperscriptBox[()), \ (2)])-25(1-!(*FractionBox[...
83 views

### How-to let user define a set of VertexCoordinates in a Graph

Here is a simple code I wrote to visualize what I am trying to achieve: C.1 ...
231 views

### Nearest Kronecker Product

Some people (see The ubiquitous Kronecker product by Van Loan) have worked on finding two matrices $\mathbf A$,$\mathbf B$ of specified size whose tensor product $\mathbf A\otimes\mathbf B$ is closest ...