# All Questions

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### 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 ...
4k views

### Torn edge paper effect for images

In my answers to Plotting Error Bars on a Log Scale I used a so called "torn edge" effect from on one of the images. @SjoerdC.deVries commented: "BTW I liked the ripped-out look of your InputForm ...
3k 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.
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### How to plot ternary density plots?

How can I get a ternary density plot just like the plots from OriginLab? ContourPlot and DensityPlot seemingly can solve the ...
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### Compiling more functions that don't call MainEvaluate

I would like to use Compile with functions defined outside Compile. For example if I have the two basic functions F and G F[x_] := x + 2 G[x_] := x And I want ...
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### Map a function across a list conditionally

It seems that this is a really basic question, and I feel that the answer should be obvious to me. However, I am not seeing. Can you please help me? Thanks. Suppose I have a list of data ...
917 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?
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### How to make MapAt work with Span?

Span (;;) is very useful, but doesn't work with a lot of functions. Given the following input ...
1k views

### What tools can help in realizing tail recursion?

I had nice discussions with Leonid and Rojo that got me interested in tail recursion. Tail recursion is not always easy to realize with Mathematica, so it would be nice to have some tools to help with ...
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### 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?
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### I'd like to display field lines for a point charge in 3 dimensions

I'd like to display field lines for a point charge in 3 dimensions. Not a force field (short arrows) but continuous field lines that start on the charge.
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### 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: ...
9k views

### Is it possible to export the equations from Mathematica to MATLAB?

Is it possible to export the output expressions from Mathematica computations (e.g., equations) in valid MATLAB syntax?
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### How do you set attributes on SubValues?

SubValues, as discussed in a previous question, are declared as follows ...
3k views

### Given a Table of Plots with some parameter, how would I mark each of the plots with that parameter

I've got a two variable function that I'm plotting against one axis for a few different values of a parameter ...
590 views

### Returning an unevaluated expression with values substituted in

Let's say I have a function formula[x_List] := (x[[1]] - x[[2]]) + (x[[3]] - x[[4]]); and I want to pass it a variable and get back the unevaluated formula with ...
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### What does # mean in Mathematica?

I asked Mathematica to compute the following Solve[c (1-x)^2-x^(1/4) == 0, x] and it returned this: x = Root[#1^8 c^4 - 8 #1^7 c^4 + 28 #1^6 c^4 - 56 #1^5 ...
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### Can 2D and 3D plots be combined so that the 2D plot is the bottom surface of the 3D plot boundary?

I have a ListlinePlot function, that I would like to combine with both a Graphics3D plot and a ...
3k views

### About the number format in ticks

I want to LogPlot a function, but I have the trouble in the number format in the ticks. For example, ...
2k 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 ...
2k views

### Way to improve “show me this decimal number to M places, don't use scientific notation”?

The best way I can come up with to say "show me this fraction as a decimal number to M places, don't use scientific notation" is: ...
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### The difference between 0. and 0

I have a function for which 0 is a special case: f[A___, 0, B___] := 0 But since I am doing numerics, sometimes in the course ...
1k views

### Create complicated text formulas in graphics

I want to put somewhat complicated, or at least non-standardly formatted, text on some of my graphics. For example, I'd like to be able to use f^[4](x) (where the ...
619 views

### Evaluating an If condition to yield True/False

I would like to decide whether an option passed to my custom function has the value Automatic or something else. This is my attempt: ...
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### 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 ...
2k views

### How to distribute proprietary Mathematica code

If I want to make package-code completely unreadable, in a way that the end-user can only call my functions, but has no way to re-engineer my definitions, how would I do that? I know I can use ...
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### How to find circular objects in an image?

How could I use morphological processing to find circular objects in an image? More specifically, I need to detect road signs. I need to get the "80 speed limit" sign from this image:
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### Are there any cases when For[] loops are reasonable?

To my mind the only reason for the existence of For[] loops in Mathematica is to allow new users with some experience in procedural programming languages to write ...
989 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. Have any new tokens been introduced since this question was first posted?
702 views

### Placement of Condition /; expressions

It is my practice to place Condition expressions on the left side of := and :> in almost ...
675 views

### Are there guidelines for avoiding the unpacking of a packed array?

Packed arrays are very useful because they save memory and generally allow speedier and more efficient calculation times. If a list of data currently stored as a packed array is unpacked, it can slow ...
811 views

### Why is the new PositionIndex horribly slow?

This issue has largely been mitigated in 10.0.1. New timings for the final test below are: ...
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### 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: ...
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### Why is there no PositionFunction in Mathematica?

Too often I have seen the programs of inexperienced users greatly slowed by using Position in an iterative fashion, when far faster would have been to compute a ...
4k views

### Density plot on the surface of sphere

I would like to make density plots of a list of (size 2 or 3) spherical harmonics on the surface of a sphere. I'd like to plot it so that each element of that list is using a different color (red ...
1k views

### Generating graphs interactively (GUI)

I want to create graphs interactively using a GUI. I thought of using a ClickPane[] environment. The code I have (in part borrowed from the Documentation) works ...
2k views

### Real Size Image Printing

I am generating a complicated graphics with Mathematica, but with objects of given sizes (e.g. a line of length 1 inch, between two points). I want to make sure that when I export the graphics, e.g. ...