# All Questions

997 views

### How to convert an image to a graph and get the positions of the edges?

I am trying to convert an image to a graph. My image is already skeletonized and looks pretty much like this: What I need to do is identify all vertices and edges, and in particular get a list of ...
456 views

975 views

### Pass function or formula as function parameter

I can write either Integrate[x^2, {x,0,3}] or f[x_] = x^2 Integrate[f[x],{x,0,3}] and get the same computation. Suppose I ...
124 views

### Is there a quick way to find a built-in function by name search?

Is there a quick way to search all built-in Mathematica functions by name? Say I want to find all functions whose name contains "Graph", such as GraphPlot, NeighborhoodGraph, Subgraph, and so forth. ...
321 views

### I ran into an error when I was trying to solve a PDE with a piecewise initial condition by NDSolve

This is a very simple one-dimensional heat-conduct equation, the only special part of it is the piecewise initial condition: ...
174 views

### How does bandwidth selection work for low-variance dimensions with KernelMixtureDistribution?

I am puzzled because this toy example (in Mathematica 8) ...
474 views

### Celebration: How to golf a marriage with a prefix free code

We all know a conspicuous member of our community got hitched recently. As most of us are not in Malta, and weren't able to fly there, I thought of a celebration question. Sort of. The challenge is ...
317 views

### non-linear trend reduction using thresholds

Doing some mappings of the earth magnetic field results in the left-hand figure below (which consists of 181 profiles): To improve this I tried a non-linear trend reduction using, for example, ...
5k views

### How can I plot the direction field for a differential equation?

I'd like to plot the graph of the direction field for a differential equation, to get a feel for it. I'm a novice, right now, when it comes to plotting in Mathematica, so I'm hoping that someone can ...
590 views

### Speed up Mathematica code involving Convolve

I'm trying to plot the averaged autocorrelation function of a random wire profile $\xi(x)$ which is build from unitsteps which are each L units long. To calculate the average I'm generating nMax ...
215 views

### Incompleteness of FindInstance

I've been playing around with Resolve and FindInstance. I know that Resolve should always ...
1k views

### Making mathematical animations with Mathematica

I recently stumbled upon the Cycloid and was working on finding its length and such when I found this animation on Wikipedia. Strikingly pretty and small in size too (66KB) So on searching how he ...
568 views

### What is the difference between Set and SetDelayed?

I have a problem with defining a function and most of time I get confused by Set or = and ...
76 views

### Need help to finish this prime signature function?

I'm trying to create a prime signature for line segments. ...
183 views

### Version differences in Parallelize

I am having a problem which I guess is due to version difference. I have to generate a list of unitary matrices, which I can do easily. However I came to know about ...
193 views

### Exporting lists to files

I am trying to write a program which will generate a list of objects and then exports it in a separate file and clears its memory. As an example I tried the following ...
2k views

### Creating Optimal “Smoothed” Contour-Type Plots (X,Y,Z) Using Mathematica 8.04

Update: data here Here is a contour plot produced in the SAS program: In this plot, variable 23405 forms the X axis, variable 20201 forms the Y axis, and outcome variable 50502 forms a pseudo Z ...
330 views

### Monochrome PNG (and GIF) Export

Is there a way to Export expressions to a monochrome PNG? I have tried the ColorQuantize function which is mentioned in ...
144 views

### How to enable-dynamics on CDF's on web?

Went through the wizard to export cdf /w embed code: The positions and sizing are correct, but there's no interactive side to it: data I'm using: ...
194 views

### BubbleChart Text Tooltip's

Is it possible to display "name" in the tooltip? It won't chart the full dataset, so I can't make a custom labeling function that takes it in. ...
308 views

### Why is slider not working properly in Manipulate?

This script is an abstraction from a script intended to plot errors in guiding a small telescope that is tracking a guide star. The data loosely imitate the kind of data one might get from the program ...
1k views

### Dealing with Empty Brackets in a List

I have a large list with varying constituent parts. Some of these are like this: i.e. graphlist[[34]] ...
350 views

### Optimizing NIntegrate for higher PrecisionGoal

By default, NIntegrate works with MachinePrecision and its PrecisionGoal is set to ...
396 views

### Evaluating an If condition to yield True/False

I would like to decide whether an option passed to my custom function has the value Automatic or something else. This is my attempt: ...
450 views

### Finding concave hull for separated small clusters

Data : data3D = Import[file, "VertexData"]; Graphics3D[Point[data3D]] How to find concave polygon for separated small clusters.
776 views

### Image Processing: Isolating areas of an image with internal irregularity

I am trying to isolate each of the blue painted fingernails in the image. However, I am not sure what approach should be considered due to the white design on each nail interrupting the otherwise ...
1k views

### Two x-axis with different units connected by function using CustomTicks

I am trying to make a plot of some photoluminescence data, where wavelength is on the x-axis, and intensity is on the y-axis. Also, I would like to have the graph boxed, with the upper x-axis having ...
172 views

### Built in way to de-list singletons?

Is there a built in method to de-list singleton expressions, like this rule-based solution: expr_ :> If[Length[expr] == 1, First@expr, expr] In data ...
308 views

### Find subexpression to minimize leafcount after replacment with temporary variable

Given an expression expr, is there an automated way to find a subexpression subexpr such that replacing ...
416 views

### Multidimensional array reduction through summation over one of its dimensions

1. Introduction I am using an array of dimension 3 (might become more) to store some values. I would like to implement a function that takes as argument the array and a couple of numbers smaller than ...