# All Questions

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### How to replace a variable that was assigned a value before

Question How to make the replacement $f[x] \to f[y]$ for an abitrary function $f$ if $x$ was assigned a value before? Example 1 How can I make the replacement $x +1 \to y + 1$ if I have assigned ...
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### Caching of Graph Graphics

In this answer, Simon Woods concludes that when you display an expression with head graph more than once, something is getting stored somewhere. I looked into it too and found out this only happens if ...
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### How to make the plot from geotiff format

I have a "GeoTIFF" format map, and I have imported it into Mathematica, then I used the Graphics to plot a point on the map. ...
82 views

### A simple StringCases problem

Given this text: text1 = " A Vitamin D Deficiency (ICD-9-CM 268.9) (ICD-9-CM 268.9) 09/11/2015 01 "; Yes, the ICD code values are duplicates- possibly but ...
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### Create/Plot Tables of sequences and partial sums

How exactly do you create and plot tables of sequences and partial sums?
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### Using NonlinearModelFit to fit data with errors

Assume we have some data of measurements SeedRandom[9]; data = Table[{i,2*(1 + 5*RandomReal[])*Exp[-0.01*(1 + RandomReal[])*i]}, {i, {0, 100, 200, 400, 700}}]; ...
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### How can I detect an ellipse in a photo?

I tried to detect the rim of the following cup as an ellipse. I've tried the solutions given in How to find circular objects in an image? to detect the ellipse, but the detection result was not ...
115 views

### The plot of roots of polynomials

I have polynomial equation like Tribonacci Polynomials for example: $T_3(x)=x^4+x$. After finding the roots of this polynomial, I want to show these roots in the complex plane. I have tried lots of ...
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### How do I get my equation to have the form $(x-a)^2 + (y-b)^2 + (z-c)^2-d = 0$?

I want Mathematica to express the equation $$-11 - 2 x + x^2 - 4 y + y^2 - 6 z + z^2=0$$ in the form $$(x - 1)^2 + (y - 2)^2 + (z - 3)^2 - 25=0$$ How do I tell Mathematica to do that?
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### Telling mathematica to output * instead of space for multiplication, so I can copy as plain text

I am trying to get some symbolic expressions in Mathematica which I would like to paste into my C/MATLAB codes. This can be accomplished nicely by selecting the expression and right-clicking to ...
29 views

### Combine absolute and relative (scaled) coordinates

I am using Inset to add an Epilog to a plot. The position of the images (in my case: framed numbers) can be specified as an ...
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### Filling and Shading an Harmonic Curve

Suppose I have an equation plotted as shown: ...
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### How to relate memory usage with occupied positions of SparseArrays?

What is the relation of memory usage of a SparseArray and the number of its occupied positions? Let's say you build a 100.000.000 by 10 element SparseArray. And fill the two position 1/1 and ...
531 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.
103 views

### Filtering the elements of an array to split them into two categories

So, I am new to Mathematica, and I am trying to write something that involves taking values from one array and separating them into two different arrays. My code for doing this is: ...
32 views

### Faster way to perform SameQ[Reduce[…], Reduce[…]]

I'm have some expressions that I need to confirm the equality of. SameQ[Reduce[...], Reduce[...]] works like a charm for the more simple expressions, however when ...
90 views

### How to draw tiles with different height?

I have a random matrix RandomReal[{1, 2}, {20, 20}], whose elements represent the heights of an array of tiles. The cross sections of each tile are square and ...
90 views

### Cell brackets on left side?

Is it possible to have the cell brackets on the left? I looked through the options and couldn't find anything, but maybe it's some kind of esoteric style setting or something. The reason I'm looking ...
96 views

### Manipulate a Plot that contains a variable that contains symbol

This snippet mm = m Manipulate[{mm, Plot[mm x, {x, 0, 1}]}, {m, 0, 1}] (m is not defined anywhere) produces a sadly fixed ...
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### Interpolation and points of non-differentiability

I have some data, which if expressed by some elementary functions, would contain a non-differentiable point. I would like to be able to use something like interpolate to convert the data into a ...
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### Correct behavior of lock file in hsqldb connection

I'm running in to some problems with generating a persistent HSQLDB and during some troubleshooting I came upon the following behavior. ...
77 views

### Precision of a complex number

In an output I'm getting a number like -0.33998187034939803 + 0.I. Finding ...
47 views

### Optimizing functions taking matrix arguments

I'm looking for general information on how to optimize matrix valued functions, I have the following function I'm looking to maximize (or figure out if this is possible at all). ...
105 views

### How to draw a contour diagram in Mathematica?

This answer at Math.SE contains a neat contour diagram created using Mathematica: What Mathematica functions I can use to draw diagrams like this?
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### Dynamic graph visualisation using JLink/Java and GraphStream

Visualising the addition of new nodes and edges to a graph to 'watch it grow' is to something Mathematica is not suited to by default. However this type of animation really helps convey the emergence ...
1k 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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### Manipulating plot of random iterated function system fractal

I'm generating the Sierpinski Gasket by implementing a chaos game in mathematica. What I'd like to do is create an interactive manipulation with a slider, whereby moving it forward, plots all the ...
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### FindRoot runs out of memory in Windows but not on Mac

I am using FindRoot to find solutions to a large, highly oscillatory equation which I generated using other code. When I run ...
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### Performance of Dispatch and lists of Rules

First of all, I have seen the question "Why is this parallel evaluation with Dispatch[] so slow?", but that seems to be a different matter. My question arose when I tried to answer this question by ...
48 views

### Question about usage of Style as Dynamic object

I saw a Dynamic snippet in this answer, which wrote ...
2k views

### What are the most common pitfalls awaiting new users?

As you may already know, Mathematica is a wonderful piece of software. However, it has a few characteristics that tend to confuse new (and sometimes not-so-new) users. That can be clearly seen from ...
59 views

### Weird vertical line when trying to plot a histogram [duplicate]

I'm trying to plot a histogram of a few data points and overlay a plot on it (it's a fit of a geometric distribution to my data). The weird thing is that a vertical line appears always next to the ...
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It is possible to define function dependently to passed argument type or condition this argument fulfills (somewhat like overloading): ...
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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 ...
99 views

### creating an API or Widget based on a Mathematica notebook

I'm trying to create matrix calculator and graph tools for our website and was wondering if there is a way to create Wolfram API or Widgets based on a Mathematica notebook.
59 views

### undisputed FrontEndTokenExecute

Thanks to that great topic, I've found FrontEndToken i was looking for: "DeleteGeneratedCells". Well it is also written in ...
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### How can I use Manipulate[] to click on a Graphics3D output and generate $(x,y)$ outputs on a projection plane parallel to my screen?

Say I have some Graphics3D object that I'm looking at from a top down perspective, e.g.: ...
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### create function that behaves like continuedFraction [duplicate]

I'm just starting to learn Mathematica and I got stuck at this question. This a noob question but please help. I need to define a function named continuedFraction that takes user input of type list ...
296 views

### Building a continued fraction

I've completed a problem that involves approximating $e$ by a continued fraction: $$\frac{N_1}{D_1+\frac{N_2}{D_2+\frac{N_3}{\ddots+\frac{N_k}{D_k}}}}$$ with the $N_i$ being the list ...
257 views

### non-linear trend reduction using thresholds

Doing some mappings of the earth magnetic field results in the left-hand figure below (which consists of 181 profiles): To improve this I tried a non-linear trend reduction using, for example, ...
22k 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 ...
147 views

### Problem with extracting specific contour from a ContourPlot

I am trying to exctract contours of specific value (2.6*10^-6) out of a ContourPlot and measure their area. Below you can see the code. It is noticable that not all of the relevant contours showed in ...
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### How do I automatically “trim” the bounding box for a Graphics3D output? [duplicate]

I noticed that, provided some Graphics3D output scaled with ImageSize, I can get rid of a lot of the empty space around the graphic by right-clicking and then selecting "Trim Bounding Box". Thinking ...
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### How to insert big list of Data in DB?

I have a list of values with length is 60000.Earlier I used this list in my App by using ...
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### extracting the rows of a matrix satisfying a condition (e.g. all elements negative)

I have a matrix with thousands of rows and want the submatrix comprising the rows of the original matrix that have, e.g. a negative element in column 3. How to do that?
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### How to keep ItemSize effect when export to HTML

Here's the simple code Grid[Table[Item[1,ItemSize->{5,10}],{2},{2}],ItemSize->{5,10},Background->Red] Save the output cell as .html file, ...