# All Questions

3k views

### How to create effect like Van Gogh's stroke brush?

I need to apply Van Gogh's stroke brush effect to a random image Take the following image as an example: Thank you so much if you could help!
119 views

### Making a predictive statistical model

I am totally new to Mathematica, and I have never used a similar program, apart from perhaps Excel (and I didn't even use Excel on a professional level). So I want to create a mathematical model ...
167 views

### How should I go about writing more functional and list based code? [duplicate]

I've heard that Mathematica is usually faster when the code is list-based and/or uses a functional paradigm. I'm still working on getting the hang of this; there are a lot of ...
185 views

### How do I construct a non-linear model from experimental data?

I want to find a function $w=f(x,y,z)$ that fits experimentally determined values of w. For example, assume ...
125 views

### Deleting elements on a list by the first element of another list

I was trying to make this L1 = {{2, 1}, {6, 4}, {8, 7}, {9, 5}}; L2 = {{2, 9}, {9, 6}}; L = Union[L2 , L1] And I used this: ...
74 views

### Defining functions that reference other values

How could I define a function that references other values? eg a = 2 x; b = 4 k; f[k_, x_] := a^b
186 views

### Is it possible to convert expressions containing Root objects to Excel formulas?

I am still a beginner and do not fully understand pure functions and root objects. When I tried to calculate the inverse of a function, Mathematica gave me: ...
887 views

### Threads vs Cores: How many kernels need to launch in parallel Mathematica?

I have a dual-core intel machine. I would like to test how many parallel local kernels should be launch to get the optimized performance. Knowing that the HyperThreading technology of Intel could run ...
81 views

### Need to run evaluation 2 times

Why does this only work after running the evaluation 2 times? ...
334 views

### Edit Plot/Graphics after it's been drawn. [duplicate]

Sometimes I run into a situation when there are graphics objects (mostly plots) that take a while to draw. Good practice would suggest you do all your evaluation outside ...
229 views

### How to simplify to form without imaginary unit

I have an integral that I compute with Mathematica and as a result I get a seemingly complex expression (i.e. the expression contains the imaginary unit, $i$, at some places). However, if I try to ...
426 views

### A fast way to compute arrays avoiding If or Which

I found out that if I have to calculate huge arrays with most of the elements being zero( let's say each row has 10000 elements and only 8 are non zero) and the non zero elements' positions being ...
35 views

### Internals of Prime function [duplicate]

Does anyone knows how exactly Prime works ? For example how Prime[1000000000] is calculated ? The only information I found was ...
90 views

### ctags for Mathematica files?

I alway use vi to edit Fortran files. I can use ctags to know which variables and functions I have already defined. Now I use vi to edit Mathematica *.m files. I tried to use ctags for *.m files, but ...
123 views

164 views

### NMinimize stops with no more memory?

I am using NMinimize function for simulation based optimization. So my objective function is a simulation that runs for every combination of variable values evaluated by NMinimize function. However, ...
311 views

### Find the best parallel lines to a given data set

I have a set of data in an uptrend. I would like to find two BEST parallel lines to contain all the data but I don't know how to approach it, anyone can help ? Thanks.
557 views

### Plot3d: How to color a surface according to the slope of the surface?

Here is my approach, for an example surface function: surface[x_, y_] := Sin[x y]; The normal vector of a point in the surface is computed as: ...
341 views

### Formatting Excel Borders with .Net

I have various tables generated in a Mathematica application and need to export this to MSExcel formatted in a specific way. The ...
587 views

### Scheduling Mathematica scripts to run from a command line [duplicate]

I want to run Mathematica "jobs" on a daily/weekly basis to do system maintenance and as part of daily processing operations. What is the best way to do this?
106 views

### Code for sum of exponential divisors function

Consider $n = p_{1}^{a_1}\cdots p_{r}^{a_{r}}$. An integer $d = p_{i}^{b_{i}} \cdots p_{r}^{b^{r}}$ is called an exponential divisor of $n$ if $b_{i}$ divides $a_{i}$ for every $1\leq i \leq r.$ I am ...
181 views

### How to construct a graph from a list of edges

I have a list of pairs of numbers, representing connections between objects in the real world. Each number is the identifier of an object, there are gaps in the range from the smallest number to the ...
41 views

### Manipulate freezing on large calculations [duplicate]

I have a sum that ordinarily takes some time (2 - 3 seconds) to calculate. When I put it into a manipulation though, it becomes very temperamental. It will work on some very small calculations, but ...
175 views

### Manipulate with formatted output

I would like to have 4 output fields for something like the following: Manipulate[ n*x n/x n + x n - x, {n, 1, 10}, {x, 1, 10}, ControlType -> InputField] but ...
110 views

### Opposite function to Normal

Is there any function opposite to Normal? For example, let as say that I have an SparseMatrix A, then, let as say that for convenience for a certain operation like Packing, I convert it into an Array ...
185 views

### Isn't it possible to Pack a SparseArray?

I have the following matrix Va: ...
818 views

### shooting method and stifness problem for NDSolve

I'm trying to solve numerically the following differential equation: 1/r[x]^5 + k/Sqrt[1 + r'[x]^2] - (k r[x]r''[x])/(1 + r'[x]^2)^(3/2) == 0 I can set boundary ...
I'm new to Mathematica, and I was wondering how to plot $x^n$ in the complex plane. Is there a dedicated function for this purpose?
Let's say that we have some $300\,\text{K}$ digits (arbitrary function) and want to trial factor with $100{,}000{,}000$ first prime numbers. ...