0
votes
1answer
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 ...
2
votes
1answer
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 ...
0
votes
0answers
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 ...
3
votes
1answer
76 views

How to import several files at once?

I tried to import multiple files at once. Following this topic my code is ...
6
votes
1answer
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 ...
1
vote
1answer
45 views
0
votes
2answers
69 views

Varying results from the Round function

My problem is simple. Consider the following. ...
10
votes
1answer
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 ...
2
votes
1answer
43 views

Simplify trigonometric expression

Mathematica correctly simplifies the following expression: ...
3
votes
2answers
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 ...
3
votes
0answers
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 ...
1
vote
0answers
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 ...
2
votes
0answers
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 ...
0
votes
1answer
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 ...
1
vote
0answers
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). ...
2
votes
1answer
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 ...
1
vote
1answer
42 views

Getting the message NDSolve::underdet:

I am solving the wave equation with initial position and velocity function: ...
15
votes
1answer
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 ...
17
votes
3answers
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 ...
3
votes
0answers
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 ...
2
votes
3answers
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 ...
1
vote
1answer
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 ...
5
votes
1answer
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 ...
2
votes
0answers
81 views

Shadowing issue with DeleteDuplicatesBy

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 ...
3
votes
2answers
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 $\sigma=0.1$: $W_t = \rho W_{t-1} + (1-\rho) \bar{W} + \epsilon_t$ ...
1
vote
1answer
73 views
0
votes
0answers
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 ...
1
vote
1answer
102 views

Why does FindFit work and NonlinearModelFit does not?

I have a somewhat complicated function that I have defined. ...
0
votes
1answer
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 ...
0
votes
2answers
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 ...
0
votes
0answers
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 ...
0
votes
0answers
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 ...
2
votes
0answers
91 views

Nasty integral advice

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 ...
2
votes
1answer
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 ...
1
vote
1answer
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 ...
1
vote
2answers
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 ...
9
votes
2answers
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 ...
0
votes
2answers
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? $$\frac{x^2}{a^2}+\frac{y^2}{b^2}+\frac{z^2}{c^2}=1$$
2
votes
1answer
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): ...
5
votes
1answer
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: ...
0
votes
1answer
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 ...
2
votes
0answers
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?
0
votes
0answers
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 ...
1
vote
1answer
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 ...
0
votes
0answers
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 ...
1
vote
1answer
49 views

Unexpected AdjacencyMatrix output [duplicate]

I have a directed graph with this Edgelist defined as follow: ...
3
votes
1answer
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 ...
3
votes
1answer
37 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 ...
0
votes
1answer
80 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 ...

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