# All Questions

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### Is the divergence between Round[] and setting an explicit precision intentional or a bug?

Introductory remark: I take it (from Mathematica's online reference), that "Precision" is effectively the number of significant digits, as seen by the system. For literals, precision is set using ...
74 views

### Polynomial expansion of operator

I am new to Mathematica, I am trying to generate the polynomial function of a operator. So for example, the operator $L$ is $\frac{\partial f}{\partial x}+\frac{\partial f}{\partial y}$, and I want ...
62 views

### Using map projections with astronomical data

I noticed that all important "Geoprojections" are available in projections for a spherical reference models: GeoProjectionData function; 1 - I am trying using the sinusoidal projection for ...
8 views

### I need help to solve this problem

Let m,n nenegative integers and m>n. Find polinom g(x),r(x) from the ring R[x] such that x^m -1 =q(x)(x^n -1) + r(x) , r(x)=0 or deg(r(x))
63k views

### Where can I find examples of good Mathematica programming practice?

I consider myself a pretty good Mathematica programmer, but I'm always looking out for ways to either improve my way of doing things in Mathematica, or to see if there's something nifty that I haven't ...
59 views

### How to efficiently get a list like this?

I want a function myfun that generates list like this ...
157 views

### Fit convoluted Gaussian and Lorentzian functions to a peak profile

I have a peak profile data like this: ...
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### BUG? SemathicImport unable to properly read an Excel file with accented letters

Apparently SemanticImport fails to properly import Excel files when accented letters are present in the first (header) row. I'm using Excel 2013 on Windows 8.1 x64 ...
22 views

### Numerical integration: complicated 2D integral seems to be poorly estimated

In the course of some physics research I've been working on, a very annoying integral has appeared that I'm having difficulty evaluating numerically. Any help you could offer would be greatly ...
44 views

### Permanently rounding numbers/values to a given number of significant figures

I am searching for a simple way of rounding and setting an input to a desired number of significant figures. There are a vast number of posts that discuss similar problems, but none address this ...
114 views

### Maximize[Cos[x - 1], x] is not evaluated

No explanation needed: Maximize[Cos[x + 1], x] Maximize[Cos[x - 1], x] producing ...
82 views

### Display level of recursion of a recursive function during execution

Given a recursive function, is there some simple way to display or store the value of recursion or "how many levels deep" the function is at a given time? For instance, if we wrote the recursive ...
272 views

### For a given expression: if it appears, remove it, but if it is absent, add it

While reformatting Szabolcs's code from (42660) I noticed this interesting operation: ...
60 views

### Is there any strategy to have a compiled version of FindFit or NonlinearModelFit?

Disclaimer: This is not a precise question with a definite answer. I know that neither FindFit nor NonlinearModelFit is in the ...
31 views

### Is there a notebook to create entries for OEIS?

Is there a notebook to create entries for OEIS? I seem to recall something like this a few years ago, but I haven't been able to find one. It might be from MathWorld. Any suggestions? Edit If I had ...
98 views

### FEM - how should I impose periodic boundary conditions in pure space problems?

I have searched other threads, but I was not successful in finding an answer I could understand. Right to the point: how do I impose correctly periodic behavior on the edges of the rectangular ...
73 views

### Unable to fit function convolved with NIntegrate with FindFit even with NumericQ

I am attempting to fit to the convolution of a simple function with a Gaussian. (I realize this could be done with Convolve also, but I thought I could make it go faster this way). I am able to ...
23 views

### Hiding a Manipulate slider

I want to generate a different random initial condition for rule 110 using a Button for Manipulate, not a slider. How can I make the slider invisible here? I tried specifying ...
104 views

### Trace two DateListPlots?

I currently have two DateListPlots in the same graph, with two different y-axes. I downloaded the package "TwoAxisDateListPlot" to accomplish this with ease. Now I want to be able to trace both of the ...
243 views

### Animate point go round a triangle

How can I animate a point moving on triangle sides? I can generate traingle and point but I have no idea how to define point movement. I'm guessing that I have to use sin and cos in coordinates but I ...
28 views

### Problem with control structures on getting root values on array [on hold]

Since mathematica control structures are a bit different from programming languages that I'm familiar with , I'm having problems. I want to assign the roots of a function to an array , but check if ...
109 views

### List Manipulation Via Conditionals

I'm trying to convert one list to another by applying a condition on the list's elements. But I can't figure out how to do this in mathematica's language. Python example below ...
44 views

### Strange behavior with Show command

I enter this: ...
31 views

### Possible to dynamically redraw single plot of multiple shown together?

I am attempting to create a tool to visualize gradient, eigenvector, and eigenvalue information for a 2D surface. I want to show a contour plot of an inputted function and overlay the gradient and ...
21 views

### CurrentImage returns almost fully black image

On Mathematica 9.0.1.0, Windows 7 SP1 Calling CurrentImage[] returns a black image, with a few non-black pixels near the top of the image, which may be some kind ...
136 views

### Is it possible to build/simulate/extract data from a System Modeler model completely inside a notebook using the MathModelica language syntax?

See examples in: http://www.mathematica-journal.com/issue/v10i1/contents/MathModelicaPaper/MathModelicaPaper_2.html It seems to be ruled out by the statement (Chapter 2 intro): "The subset of the ...
18 views

### LineScaledCoordinate problem for exact coordinates

There appears to be a bug in LineScaledCoordinate I've faced writing an answer for Animate point go round a triangle. For coordinates with exact values, instead of ...
31 views

### How do I plot 3 (x,y,value) on a Histogram3D[] function?

I have been trying to plot data using the Histogram3D function but I've had no luck, in excel I have x, y and a value I want to plot for each pair, do I have to save this as a data file first? I have ...
71 views

### Why does ToRules return a Sequence?

Why does ToRules return a Sequence expression? Why doesn't it return directly what ...
37 views

### ControlType -> None Vs. Module inside Manipulate (i.e. making everything local)

I'm building a program on another one made available in the Wolfram Demonstration Project. I've noticed that in the original code (working flawlessly) many variables were made local inside the ...
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### Probability of multivariate normal being positive on each coordinate

How can I find the probability that each coordinate of a specified multivariate normal distribution is positive? I tried the following, which I believed should work ...
70 views

### WorkingPrecision causes issue in the NIntegrate

I really can't figure out why my code sometimes is not working. My integrations involve two variables (k and kz). The integration range for both of them are from zero to infinity. I found out that in ...
90 views

### Proving large inequality in 6 variables

I have arrived at a very large inequality in 6 variables that I would like to prove is true. The command I have tried is the following: ...
52 views

### how to solve line and ellipse equations in 3D? [on hold]

I have a point and a vector to find the line equation, and ellipse equation in 3D. I need to solve the two equations of line and ellipse in 3D. how can I do this, what equations should I use?
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### Compress uses too much memory and sometimes crashes the Kernel

Using Compress is a good idea to save memory when working with large expressions. The problem is that Compressing large expressions also uses a large amount of ...
59 views

### Preventing complex term in a differential equation solution

I am solving the initial value problem: $$y'=\frac{t+1}{t(t+4)},\quad y(-1)=0$$ I believe the correct answer is $$y=\frac14\left[\ln(-t)+3\ln(4+t)-3\ln 3\right]$$ with an interval of existence ...
90 views

### Obtaining the relations of variables using diagonal matrices

I know this is too an elementary question, but I am a pathetic newbie in mathematica and I cannot find any answer by googling. What I want is obtaining some relations of unknown variables using their ...
97 views

### Fick's Law over Implicit Regions

I'm trying to solve 2D Fick's law of diffusion from the boundaries of a triangle (future shapes will include more complex implicit regions). I'm able to model diffusion without time in complex ...
83 views

### Boundary sphere partial differential equation

I am trying to solve partial differential equation in spherical coordinates $(\theta,\phi)$,but I don't know how to properly include boundary conditions of $\theta$. For $\phi$ it is periodic, but ...
34 views

### Import table from txt file with specific rows

I have a .txt file written as 1 2 3 4 5 6 7 8 9 10 11 12 I would like to import it as three matrices according to the rows. I used b = Import["d:\am.txt", {"Table", Range[1, 2]}] Seems it ...
107 views

### How can I get all solutions of a system of equations with Reduce?

The post What is the difference between Reduce and Solve? discusses the difference between Reduce and Solve. Now, with the ...
96 views

### Differential equation with a Heavisidetheta function running for ever

So I'm trying to get the solution of the following differential equation: ...
21 views

### How to “reduce” a probability distribution satisfying certain conditions [migrated]

I will try and explain the question I have in term of an example. I am given some probability distribution $f$, in this case of 2 variables x and p, $f(x,p)$. For example, I can pick the ...
108 views

### Get the complement date range

Suppose that I have a date range list drlist = {{"2015-01-01", "2015-01-05"}, {"2015-01-07", "2015-01-07"}, {"2015-01-12", "2015-01-23"}} ...
62 views

### ordered tree data structure

I have a map $f:X\to \mathbb{N}$ and I wish to find $x,x'\in X$ such that $f(x)=f(x')$. Since such elements are rare, I will have to check very many elements and perform many comparisons, so I suspect ...
17 views

### Graphics3D loses interactivity in Dialog window

Is there a way to keep Graphics3D objects manipulable when they are embedded in a Dialog window (CreateDialog,...
75 views

### $3\times 3 = 6 + \bar{3}$ in Mathematica?

Can Mathematica handle this type of algebra? That is, I want to decompose a product of representations (in $SU(N)$ say) into irreducible ones. How can one do that with Mathematica? A very brief ...
688 views

### How to Map a subset of list elements to a function?

How would you, given a list {1, 2, 3, 4}, apply a function f to 1 and ...