3
votes
0answers
23 views

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 ...
2
votes
2answers
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 ...
2
votes
1answer
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 ...
0
votes
0answers
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))
321
votes
12answers
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 ...
1
vote
2answers
59 views

How to efficiently get a list like this?

I want a function myfun that generates list like this ...
0
votes
1answer
157 views
0
votes
0answers
11 views

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 ...
1
vote
0answers
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 ...
1
vote
2answers
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 ...
15
votes
1answer
114 views

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

No explanation needed: Maximize[Cos[x + 1], x] Maximize[Cos[x - 1], x] producing ...
4
votes
1answer
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 ...
10
votes
5answers
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: ...
0
votes
1answer
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 ...
1
vote
0answers
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 ...
4
votes
1answer
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 ...
2
votes
2answers
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 ...
1
vote
1answer
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 ...
1
vote
1answer
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 ...
4
votes
4answers
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 ...
-1
votes
0answers
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 ...
2
votes
4answers
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 ...
2
votes
2answers
44 views
1
vote
1answer
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 ...
0
votes
2answers
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 ...
0
votes
1answer
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 ...
1
vote
1answer
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 ...
1
vote
1answer
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 ...
6
votes
2answers
71 views

Why does ToRules return a Sequence?

Why does ToRules return a Sequence expression? Why doesn't it return directly what ...
1
vote
0answers
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 ...
1
vote
2answers
71 views

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 ...
2
votes
2answers
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 ...
2
votes
0answers
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: ...
0
votes
1answer
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?
3
votes
0answers
43 views

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 ...
1
vote
1answer
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 ...
0
votes
2answers
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 ...
3
votes
1answer
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 ...
3
votes
1answer
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 ...
0
votes
2answers
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 ...
4
votes
2answers
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 ...
3
votes
3answers
96 views

Differential equation with a Heavisidetheta function running for ever

So I'm trying to get the solution of the following differential equation: ...
0
votes
0answers
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 ...
3
votes
3answers
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"}} ...
2
votes
1answer
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 ...
1
vote
1answer
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,...
6
votes
0answers
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 ...
11
votes
7answers
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 ...
10
votes
0answers
68 views
1
vote
0answers
58 views

Good sources of programming exercises for learning Mathematica programming? [duplicate]

I'm learning Mathematica programming. I wonder if there are any good sources of programming exercises particularly suitable for practicing Mathematica programming.

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