# All Questions

350 views

### What is the difference between a .wl package and a .m package?

In Mathematica 10.x, one now has both .wl Wolfram Language Packages and .m Wolfram Mathematica Packages. What's the ...
84 views

### Solving a second order ODE numerically

I am trying to solve the following second order linear ODE numerically (for small w, say) y''[x]+ D[f[x],x]/f[x] y'[x]+ w^2/(x^2 f[x])^2 y[x] == 0 where, ...
369 views

### intersection between polygon. Algorithm to check it [closed]

I'm working on an algorithm which should check if two polygons, described by their vertex coordinates, are: one inside the other, are intersecting or are separated image below describe this three ...
101 views

### Parsing tab delimited file

Problem Description I have my data arranged in a tab delimited file and I'm trying to parse/access certain parts of it. As an example, I'd like to extract the number of points and the sampling ...
141 views

### How to be more efficient/faster with this MatrixExp-vector multiplication?

I am looking for expertise that helps to improve speed of the code below. First, a little bit of background: There is some system of differential equations $\dot{\vec{m}}(t)=S(t)\vec{m}(t)$. In order ...
81 views

### Is it possible to avoid the singularity problem of a 2nd order differential equations by restricting the solution range?

I would greatly appreciate your help in implementation of Mathematica for solving a 2nd order differential equation expressing some important engineering problem. Apparently, this equation has no ...
130 views

### Two overlapped spheres with boundary lines

How can I have two overlapped spheres given by ...
98 views

### Converting Units in formula

I have the following formula ...
327 views

### Smallest element distance between two lists

I have a problem, where I generate two lists of points, and I want to see which points are the closest. If I just want to find which ones are exactly the same, I can use ...
81 views

### How to use patterns to return non-overlapping sequences of consecutive elements from an array

Let me first describe the data structure I'm looking at before describing my question. I have an array of nx3 elements with a data-generating process such that each row has the format: {previous ...
81 views

### MySQL insert statement over remote server is extremely slow. How can I speed it up?

I need to insert values to a remote MySQL server. However it is extremely slow compared to a local MySQL server. This is my timing for the local MySQL server ...
66 views

316 views

### How can I find solutions for this equation?

I have a function cxyz[s1, e1, s2, e2], and I want to find at least one set of {s1, e1, s2, e2} for which the function's output ...
48 views

### Assumption that a parameter is real [duplicate]

I'm making some calculations, where I use the command Conjugate[f[x]]. In the function f[x] appears a parameter J, which is Real. How can say mathematica that it should not take the Conjugate of J? ...
195 views

### How to speed up a For-loop [closed]

My code is the following: ...
52 views

### Problems with solutions obtained from Reduce

I am solving a problem using Reduce, and having a difficulty with understanding the answers I obtained. I was solving ...
111 views

### How to specify the plot region for ListPlot3D?

Now I'm trying to solve a PDE and the solving domain is not regular, suppose it is a map. I used the finite element method to solve it and every nodes' value have been got, and now I want to use ...
83 views

### How can I create a chart like CandlestickChart, but for non-financial data with something other than dates as the abscissæ?

I'd like to create charts reporting on Monte-Carlo experiments using something like a candlestick chart: four figures for each run with a varying parameter, eg min, mean - σ, mean + σ, max of the ...
62 views

### Multivariate Path Construction using Sobol numbers

I am sharing my code,which I have tried to perform as per the instruction mentioned below. Please correct it so that I could get my output. Instruction: Use the first m dimensions of the Sobol vector ...
45 views

### How to label outputs from Print [closed]

I have problem with Print in Mathematica. The data that I get from it, is not labelled so that I can use it elsewhere, therefore I have got to label them manually. ...
80 views

### ColorDataFunctions applied to Tables of Graphics?

I'm trying to make a graphic according to a List, n. n has integer values that go from ...
131 views

### Trying to model a system of differential equations for outbreaks

I have this SEIR system of differential equations for modeling pandemics ...
74 views

### What does the Combinatorica function: NumberOfPermutationsByType return?

I am using Mathematica 9. If I input: NumberOfPermutationsByType[{2, 2, 1, 1}] Mathematica returns 1/8. I was expecting ...
143 views

### Update or Animate an ArrayPlot or MatrixPlot?

I am trying to add new row or column or points to a 2D plot as I keep generating the values. The trick is by using this method I will not be required to store the big array or matrix and will be ...
516 views

### Difficulty understanding difference between == and ===

After doing this: ...
43 views

### Why does this form of piecewise function cause a general stop message? [closed]

I am currently learning about Mathematica by reading the book Mathematica by Example, 4th Edition. In that book, a piecewise function was defined as follows: ...
75 views

### How to make the choice list for one PopupMenu depend on the choice in another

Code fragments below ...
123 views

### Animate FromQuarternionTo3DRotation nb file with 4 quarternion values

I have a csv file. Inside the csv file, there are few rows of 4 quartenion values. I would like to animate the quarternion nb in http://demonstrations.wolfram.com/FromQuaternionTo3DRotation/ I ...
169 views

### stop notebook evaluation when Assert fails

I would like a notebook evaluation to entirely stop when an Assert fails, without quitting the kernel. Is this possible (e.g., by setting ...
132 views

### How can I make a smoothed 3D plot from a list of data? [closed]

I have a list of data points that I would like to turn into a 3D Surface with adjustable degree of smoothing for readability. The data consist of absorption values between -0.01 and 0.01 measured at ...
204 views

### PoincareSection for a driven damped pendulum is not generating a Poincaré section at all, why?

So I have the general code from the PoincareSection documentation that is changed up for a Driven Damped Pendulum: ...
41 views

### Problem on special functions

What does the symbol PolyLog^{(0,1)}(0,1/e) mean? I know the meaning of the Polylogarithm, but what is that exponent? It happens the same with the Lerch zeta function!! Thanks in advance.
218 views

### Defer, Hold, Unevaluated, Inactivate — which one when?

What are some guidelines on which function to select from among the superficially similar functions Defer, Hold, ...
60 views

### Getting numerical values from integrated interpolating function [duplicate]

I have a list of data. I integrate them with interpolation. Lets say is the following: InterpolatingFunction[{{0.01, 4.82}}, <>][x] However, is that ...
124 views

### Estimated Variance in LinearModelFit

Suppose that lmModel is a linear model which is fit using LinearModelFit. How come ...
72 views

### Interpreting Mathematica's expression for a function domain

When I study the domain my function f: f[x_] := 2/(Cos[x]^2) + 1/Log[Sin[x]] FunctionDomain[f[x], x, Reals] I receive the ...
151 views

### Efficient and fastest way to execute 4 nested loops

I have a question regarding the use of ParallelDo. I tried to parallelize the following code involving four nested Do loops by ...
114 views

### How to implement a Kalman Filter

Below I use low level code to reproduce the example of a Kalman Filter on pages 16-20 found here. First I create the data. ...
92 views

### Why must I specify the Global context for a symbol in a private package?

I have written two versions of the function below in a package. When I load the package and call the function, Why does the first version where the variable s has no explicit Context return the long ...
42 views

### Piecewise in 2D with quadrants as conditions

I am trying to define a piecewise vector field. Can the condition be of the form I am using (i.e. a quadrant)? I can't also make Piecewise work with more than two ...
106 views

### How to force MatrixPlot to differentiate distinct expr?

I thought MatrixPlot can differentiate different expressions in color until I found this: ...
118 views

### How can I run a cron scheduled task in Mathematica?

Mathematica doesn't have a built-in Cron scheduler. How can I use scheduled tasks in order to implement one ?
76 views

### Who can explain the strange behavior of command “Last”

Situation I use Last to extract the last element of an expression. Let poly=a+b*c+Log[a]+z. Problem When Using ...