# All Questions

69 views

### How to solve time dependent coupled differential equations? [closed]

I am trying to solve time dependent coupled differential equations with know initial conditions. I am just a beginner in terms of coding so would really appreciate if someone can give me an example of ...
111 views

### Need Help Writing code to find Capparelli Partitions

I am trying to add multiple criterion to IntegerPartitions[n] so that it sorts only partitions that fit the criterion. It creates a list of list of numbers in ...
31 views

### Evaluation stops, no error

I'm trying to iterate NIntegrate using Table so that I can plot the result as a function of an external angle. It's an oscillatory function so it gives some error on the estimate for the value, but ...
76 views

### How to import several files at once?

I tried to import multiple files at once. Following this topic my code is ...
94 views

### Split list into overlapping sublists

I would like to split a list into overlapping sublists! I want to generate a first sublist with a specified number of elements. Then I want to shift one element to the right and generate an ...
45 views

### Simplifying normalized eigenvector, taking into account the freedom to choose phase

If we look at the simple matrix ...
69 views

### Varying results from the Round function

My problem is simple. Consider the following. ...
388 views

### Nintegrate has memory leak

Bug introduced in 6.0 and fixed in 10.2.0 NIntegrates uses memory and does not release it. For long loops with NIntegrate ...
43 views

### Simplify trigonometric expression

Mathematica correctly simplifies the following expression: ...
38 views

### Why doesn't variables take value from manipulate?

I am new to Mathematica and I am working on a code on which the final output depends on variables evaluated from the inputs A simplified example: (x,y) inputs ,(q,w) intermediate values, (z) output ...
78 views

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79 views

### Importing large number of frames form Video - improved method?

I am trying to work with large numbers of frames from a video (30000+). I see there are a number of answers out there, but I find none of them satisfying - see below for details. I understand from ...
25 views

### Minimizing values of expressions dependent on more variables [closed]

I need to enforce seven expressions dependent on seven variables to be zero. However, the expressions are quite complicated and generaly I get a system of transcendental equations which only sometimes ...
45 views

### Factor fraction, where variable occurring in both, numerator and denominator, only appears once

I have an expression like $$\frac{1+a^2+2 a \cos\left(p\right)}{\left(1+b^2\right)z-1-a^2-2 \left(a+b z\right)\cos\left(p\right)}\text{.}\tag{1}$$ Is there a combination of Mathematica functions to ...
43 views

### NIntegrate and memory use [duplicate]

I wonder why NIntegrate uses memory. I have a long integral computation repeated thousands times. The memory use then goes up and speed goes down. I think I spot a ...
52 views

### Compile a listable function to be applied over list of lists [closed]

Consider a simple function g[x_,y_,z_] := x + y + z; (indeed, any multivariate function g will illustrate the same thing). ...
58 views

### Efficient way to apply linear function to multivariate polynomial [closed]

Suppose I start with an expression that is a multivariate polynomial in $x_k$'s, $$W = a + b \cdot x_1^{n_1} x_2^{n_2} x_3^{n_3} x_4^{n_4} + c \cdot x_1^{m_1} x_2^{m_2} x_3^{m_3} x_4^{m_4}$$ where ...
42 views

### Getting the message NDSolve::underdet:

I am solving the wave equation with initial position and velocity function: ...
536 views

### Use Compile to improve performance

I've recently discovered Compile as a way to optimize my code. I wrote a program to learn something new about Compile. I have a ...
485 views

### How to find numerically all roots of a function in a given range?

It is common that I search numerically for all zeros (roots) of a function in a given range. I have written two simple minded functions that perform this task, and I know of similar functions on this ...
74 views

### Change the background color of matched strings when doing find-and-replace

This is not a fundamental question, but it puzzles me. In doing a Find & Replace for some string in a notebook, the matched string is highlighted temporarily with some background color (green for ...
105 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 ...
55 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 ...
83 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 ...
81 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 ...
130 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 $\sigma=0.1$: $W_t = \rho W_{t-1} + (1-\rho) \bar{W} + \epsilon_t$ ...
73 views

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

I have the following package: ...
53 views

### using interpolation for data of aTable

I have a Table in which a first column is r between {0,2} and the second column is ...
102 views

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

I have a somewhat complicated function that I have defined. ...
59 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 ...
84 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 ...
68 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 these? And how can I get rid of ...
54 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 ...
91 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 ...
44 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 ...
44 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 ...
57 views

### AxesLabel style like in FrameLabel [closed]

I would like to use ListPlot without Frame. But AxesLabel produces y-label above the y-axis ...
103 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 ...
106 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? $$\frac{x^2}{a^2}+\frac{y^2}{b^2}+\frac{z^2}{c^2}=1$$
53 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): ...
114 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: ...
73 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 ...
47 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?
33 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 ...
31 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 ...
36 views

### Detect abnormal values [migrated]

Suppose that we have a monotonic sequence, and one of the values in this sequence is abnormal (it can be less or higher than the "true" value). How can we detect it? Could you suggest a good ...
49 views

I have a directed graph with this Edgelist defined as follow: ...
154 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 ...