20
votes
2answers
6k views

Can Reduce *really* not solve for x here?

Sometimes I get the feeling I'm just flailing blindly with Mathematica. Is solving for $x$ in the equation $$ \frac{\cosh (x/2)}{x} = \sqrt{2} $$ really beyond the scope of Mathematica? I try to ...
13
votes
10answers
2k views

Fibonacci Sequence Generator

I'm trying to write a function in Workbench which will generate a Fibonacci sequence starting with F0 = 0 and F1 = 1. So far I ...
8
votes
2answers
328 views

Unexpected behavior of rule matching a pattern

I am a beginner exploring the world of Mathematica. I expected the following code T[6, 5, 4, 1, 2, 3] /. {T[a___, 1, b___] -> Length[List[b]]} should return ...
10
votes
1answer
420 views

Confused by (apparent) inconsistent precision

$$ e^{\pi \sqrt{163}} \approx 262537412640768743.99999999999925 $$ E^(Pi Sqrt[163.0]) N[E^(Pi Sqrt[163.0]), 35] NumberForm[E^(Pi Sqrt[163.]), 35] returns <...
519
votes
6answers
170k views

xkcd-style graphs

I received an email to which I wanted to respond with a xkcd-style graph, but I couldn't manage it. Everything I drew looked perfect, and I don't have enough command over ...
60
votes
3answers
5k views

Metaprogramming in Mathematica

Being functional, and having no "quotation", i.e. essentially treating data and programs semantically same, Mathematica seems naturally capable of doing metaprogramming. But could anyone construct a ...
52
votes
3answers
2k views

The clearest way to represent Mathematica's evaluation sequence

WReach has presented here a nice way to represent the Mathematica's evaluation sequence using OpenerView. It is much more clear way to go than using the standard <...
38
votes
2answers
2k views

Automating Esc [[ Esc formatting?

Is it possible to program the Front End to automatically format double square brackets without having to type Esc[[Esc each time? It's awful to have to type Esc ...
17
votes
2answers
2k views

Open Excel file with Mathematica

I would like to open an Excel file and manipulate it as a COM object. While I'm able to open an instance of excel with ...
30
votes
3answers
913 views

How to flush machine underflows to zero and prevent conversion to arbitrary precision?

I'm working on some pretty intense computation in Mathematica; when my code started running slowly, I tracked the source of the problem to Exp[]. I need to ...
26
votes
6answers
642 views

Constructing symbol definitions for With

I would like to be able to define two arrays, one containing symbol names and one containing the values of those symbols, for use in constructs such as With. For ...
20
votes
5answers
2k views

How to pass a symbol name to a function with any of the Hold attributes?

Given a function with the attribute HoldFirst, HoldAll or similar, and a variable, list, how ...
28
votes
4answers
4k views

Is it possible to prerender animation in Wolfram Mathematica?

I have a DensityPlot which is evaluated for a long time. I wish to use it with animation, but it is absolutely inapropriate. Is it possible to render animation ...
21
votes
2answers
1k views

How can I conveniently call igraph from Mathematica?

Mathematica has lots of functions for working with graphs and networks, but there are still some functionality holes that are provided by other packages. Also, due to the nature of graph theory, ...
11
votes
5answers
3k views

How to find rows that have maximum value?

Suppose if I have following list { {10,b,30}, {100,a,40}, {1000,b,10}, {1000,b,70}, {100,b,20}, {10,b,70} } How to find rows that have max value in ...
7
votes
2answers
7k views

Plot 4D data with color as 4th dimension

I have a list of 4D data (x position, y position, amplitude, wavelength). I want to plot x, y, and amplitude on a 3D plot and have the color of the points correspond to the wavelength. I have seen ...
3
votes
2answers
540 views

A problem about function N

Toady,I have a problem about N,described as below: For example N[1/3, 5] (* ==> 0.33333*) and ...
20
votes
1answer
598 views

Using Evaluate and Evaluated -> True in Plot

A few use cases: (1) This, as expected, returns (almost) immediately: f[x_?NumericQ] := Evaluate[(Pause[1]; x)] Plot[f[x], {x, 0, 1}] (2) This takes ...
52
votes
4answers
7k views

Placing a ContourPlot under a Plot3D

I would like to combine a 3-dimensional graph of a function with its 2-dimensional contour-plot underneath it in a professional way. But I have no idea how to start. I have a three of these I would ...
66
votes
4answers
2k views
44
votes
7answers
25k views

Labeling individual curves in Mathematica

I need to create a plot for export and inclusion in a report. Is there a better way to label curves than PlotLegends? From what I've read and my personal experience,...
44
votes
5answers
6k views

How can I extract data points from a black and white image?

Consider the following graph (source): Is there any way to extract the data points from this image in a semi-automatic way? I have seen, and tried the methods suggested in this question, but they ...
53
votes
6answers
4k views

Does Mathematica have advanced indexing?

I have two $M \times K$ arrays $L, T$ where I would like to set all the elements in $L$ to zero whenever the corresponding element of $T$ is greater than 15. The ...
37
votes
2answers
3k views

Is it possible to change the colors of the highlighted code in the Mathematica frontend?

With Format -> Edit Stylesheet... it is possible to adjust text-properties, text-colors, formatting of equations, etc of a notebook and to use this style-definitions again by installing it as ...
34
votes
4answers
4k views

How can I make an X-Y scatter plot with histograms next to the X-Y axes?

I just saw a nice plot there: How could I implement that in Mathematica — by which I mean the plot structure, not so much the styling.
41
votes
3answers
5k views

Extract current viewing parameters from a 3D view?

Is there a way to find out the current viewing parameters of a 3D view? What often happens is that I create a view, for example: ...
43
votes
3answers
3k views

How to find out which method Mathematica selected?

There are commands like NonlinearModelFit[] or NDSolve[] that have the option Method it ...
31
votes
5answers
1k views

What is the complete list of valid Front End Tokens?

What is the complete list of valid Front End Tokens? Preferably, by version number. Keywords: FrontEndToken, ...
23
votes
2answers
10k views

How to calculate contour integrals with Mathematica?

How to calculate the integral of $\frac{1}{\sqrt{4 z^2 + 4 z + 3}}$ over the unit circle counterclockwise for each branch of the integrand?
30
votes
2answers
1k views

Can a Trie be implemented efficiently?

What is the most space and time efficient way to implement a Trie in Mathematica? Will it be practically faster than what is natively available in appropriate cases?
41
votes
2answers
1k views

Why does Simplify ignore an assumption?

Here is the example: Simplify[x + y, x + y == a] Simplify[x + y, x + y == 5] Mathematica 9 output: x+y 5 I expect the ...
31
votes
7answers
2k views

How to select minimal subsets?

I am a newbie, so please point me in the right direction if you feel this question has been answered somewhere else before. Here goes: Suppose I have a list like this: ...
27
votes
3answers
2k views

How to load a package without naming conflicts?

This question applies to any package, but I encountered this problem while working with graphs. There are symbols in the Combinatorica package (such as ...
19
votes
3answers
604 views

What are the requirements for a well behaved indexed variable? Subscript, ToExpression, Downvalue?

On writing this answer I needed to call a function, (NonlinearModelFit) with an unknown number of parameters. We have learned that we should not use ...
23
votes
3answers
2k views

Reading periodic elements from a large file

I have a large binary data file (big endian) with 100+ million "rows" of 11 elements, combination of floats and integers. This is the format: ...
22
votes
1answer
641 views

Shorter syntax for Fold and FoldList?

I find it tedious to write out the following: a = {1, 2, 3, 4}; Fold[f, First @ a, Rest @ a] f[f[f[1, 2], 3], 4] It ...
16
votes
3answers
6k views

Find all roots of an interpolating function (solution to a differential equation)

I'm trying to find all the roots of the solution to a differential equation. Using NSolve or Reduce I don't get the roots, so I'm using an iterative method which I found in physicsforums.com. This ...
13
votes
6answers
6k views
18
votes
3answers
1k views

Optimising 2D binning code

I have a set of (x,y,z) data, 45,000 to be precise and I want to bin the z values in 256 equidistant bins based on their (x,y) values. The final array should be a set of 256x256 array with each slot ...
19
votes
3answers
2k views

Removing unwanted appearance of underlying mesh

Let us first define two positive definite matrices: M1 = {{2, -6}, {4, 8}}; M2 = {{2, 3}, {4, 8}}; then set two points ...
18
votes
2answers
2k views

Basins of Attraction

How does one shade the basin(s) of attraction of a phase plot in Mathematica? I have been trying to do this using the system $$\begin{align*} \dot x &= y\\ \dot y &= -9\sin(x) - 0.20y \end{...
16
votes
8answers
3k views

extract values from replacement list

Solve returns a list of replacement rules In: Solve[x + y == 3 && x - y == 6, {x, y}] Out: {{x -> 9/2, y -> -(3/2)}} I am only interested in the ...
11
votes
3answers
1k views

PolarPlot render oddities

I apologize if this is a obvious question and answer, I don't often use Mathematica to display plots or graphics in general to be honest. So, I was tutoring my cousin yesterday in relation to Polar ...
13
votes
2answers
10k views

How to specify assumptions before evaluation?

If I request mathematica evaluate an integral for me, I'll often get a more general ConditionalExpression than I want. Example : ...
3
votes
3answers
595 views

Help on evaluation control?

I want to plot series of slopes: x, 2x, 3x, 4x, 5x, 6x... I'm trying to do this: ...
112
votes
3answers
6k views

How to make use of Associations?

I have been curious about it for long. Now that Mathematica 10 arrives, I think it's time to ask the question: How the new Association data structure would be used ...
59
votes
4answers
8k views

How to make a 3D globe?

There are many ways to create a 3D Earth that is rotatable (see here, here, related here), but most of them have some drawbacks. These issues mainly stem from either ...
54
votes
1answer
625 views

How to simplify writing LibraryLink code?

LibraryLink is an API for extending Mathematica through C or C++. It is very fast because it gives direct access to Mathematica's packed array data structure, without even needing to make a copy of ...
70
votes
3answers
2k views

Automatically generating a dependency graph of an arbitrary Mathematica function?

Has anyone written a function to pull the function dependencies of a function? That is, it would be nice to have a function that returns a list of function dependencies as a set of rules, terminating ...
40
votes
4answers
6k views

Saving data inside a notebook so that I don't have to run it again?

Piggybacking on this, I am somehow not fully convinced that I can't save data generated by a calculation in a mathematica file so that when I re-launch said file, I wouldn't have to run my ...

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