# All Questions

1k views

### How to plot the contour of f[x,y]==0 if always f[x,y]>=0

I've been stuck at this problem for weeks and I've asked several related questions here: ContourPlot shows only part of the contours [duplicate] How to plot the contour of the radius part of a ...
339 views

### Avoiding zero (empty set) solution with NDSolve

I'm trying to use NDSolve for a chemical kinetics equation where the rate of conversion is given by this relationship as typed in Mathematica: ...
110 views

### step by step interactive indefinite integral

WolframAlpha can give step by step solution for indefinite integral. There seems to be similar question but for derivatives. Is there a way that I can generate my own step by step solution for ...
186 views

### Find if element exists in N-dimensional array

I was wondering if there was a more elegant way of finding whether an element exists in an N-dimensional array. The way I would do it is: ...
492 views

### Can TreeForm be displayed “sideways”?

One recurrent problem I'm having with displays generated with TreeForm is that the expressions to be so displayed often at least one level with many (> 20) nodes ...
110 views

### Why can't I remove the {0, 0} in Circle[{0, 0}] using pattern matching?

Why does Circle[{0, 0}] /. List[_?NumericQ ..] :> Sequence[] return Circle[{0, 0}] yet ...
580 views

### How to examine the structure of Graphics objects

One difficulty I'm encountering in studying the structure of Graphics objects is that I have not yet found a way to print or display such structures that are ...
642 views

### Function to subdivide interval into n evenly-spaced points

[This post needs better tags than I could come up with. Edits to the tags would be particularly welcome.] I realize that it is trivial to define a function that takes an interval (i.e. two ...
201 views

### How to plot the contour of the radius part of a complex function

Suppose we have a complex function $f(x,y)$, in which x and y are real variables. In theory we can write the function into the polar form $$f(x,y)=r(x,y)e^{i\theta(xy)}$$ where $r(x,y)$ and ...
194 views

### Structure of Graphics (esp. those produced by Plot, ListPlot, etc.)

I'm looking for a description of the structure of Graphics objects, aimed at the advanced Mathematica programmer. The motivation for this question is the ...
142 views

### String to File removing quotation marks

If I print a string to a file it also adds quotation marks to the string. Here is an example: a = "test \t test" a >> file FilePrint["file"] How can I ...
115 views

### How to expand multiple cells at once?

Is there a simple way to expand multiple cells simultaneously? At the moment I am primarily interested in fully expanding "in one fell swoop" all the cells in a documentation window, although I can ...
490 views

### How to plot the Euler's formula in 3D?

In Von Neumann's stability analysis of Finite Difference Equations, the Euler's formula is used to describe a perturbation. Now the finite difference equation is stable if this perturbation does not ...
103 views

### How to explain the result of the two functins?

How to explain the result of the two functins? Input1: ...
356 views

### How to make a filled Ellipsoid?

I want to make a filled Ellipsoid, but it seems Filling options doesn't work in Graphics ...
2k views

### Sum all numbers from 1 to 1000 divided by either 2,3,5 or 7

How do I find the sum all numbers from 1 to 1000 divided by atleast one of 2,3,5 or 7? EDIT: I am sorry for complicating this, but I need it to work for 10^11. So anything that requires too much heap ...
108 views

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656 views

### Obtain a stable solution using NDSolve

I am trying to solve a partial differential equation using NDSolve. When I am not specifying any method options with NDSolve, it ...
257 views

### Setting a Counter in Mathematica Notebook

I would like to write a book using Mathematica, but I will write one chapter on several files. How to tell Mathematica that the BookChapterNumber pointer has the ...
2k views

### How to plot periodic function's graphic?

How to plot periodic function's graphic? For example, f(t) = t when -5<t<5 && f(t+10) = f(t) ...
268 views

### How to interpret an image histogram and plot histogram3D for an image?

I'm really finding many ambiguities in how I really should interpret the histogram of an RGB image? I could understand what the height denotes, but did not understand how the pixels get plotted on a ...
82 views

### Insert glyphs into a string using functional code

I asked this question few days ago: Replace For-loop with functional code Suppose I use strings instead of lists; for example a = ToString /@ {123123, 112233};` ...
506 views

### How to write plain Greek in a text cell

If I create a text cell and type some greek text, most of the symbols are italics as if the cell had an Input style. It doesn't happen with latin characters. I recollect that it is impossible to fix ...
422 views

### ContourPlot shows only part of the contours [duplicate]

Consider these contour plots: f[x_,y_]:=Cos[x] + Cos[y] ContourPlot[f[x, y] == 0, {x, 0, 4 Pi}, {y, 0, 4 Pi}] ...
57 views

### can someone how to plot $x = c$ in a different color scheme? [duplicate]

Exactly as title says. I do not know why I am having so much trouble with this. I have googled many solutions and I cannot find a straightforward answer. Also, the only method I know is "Gridlines" ...
676 views

### What's the cleanest functional-programming style way to perform this list operation?

I am looking for the correct method for accomplishing the unknown piece in the following code snippet: rolls = Tuples[Range[1, 4], {2}] ...
263 views

### Long text inside a grid does not word wrap

If I create a simple grid with Ctrl+, and paste a long piece of text outside the boxes (I'm sure you can find some yourself), then that text does not break at the width of the window in Mathematica. ...
459 views

### Solving a diffusion equation

I need to solve a particular diffusion equation with NO boundaries http://astronomy.nju.edu.cn/~chenpf/c/courses/fluid/pringle81.pdf equation (2.10) with nu = cost. ...
183 views

### Plotting data with 4 columns!

I'd like 3Dplot a list of data with 4 columns (these are mesh outputs): x1 y1 z1 Dose1 x2 y2 z2 Dose2 . . . which command i ...
119 views

### How can I plot the integral of a unit tangent vector? [closed]

The questions states: Let r[t_]:= {E^(-t), 3t^2, 4 Sin[t]} Plot and compare r[t] and the integral of ...
67 views

### Combine 2D images perpendicular to each other [duplicate]

I would like to create a slice plot from multiple density plots in Mathematica. A solution for this probem has been posted in this forum before (Is there something like DensityPlot3D?). But how would ...
339 views

### Finding max value of each column of 4x4 Array

I have the following array in both MatrixForm and List form ...
341 views

### Problem in units convertion when multipliying Boltzmann constant and a temperature

When define the temperature of a variable in Celsius, Mathematica 9.0 does not calculate the right answer when multiplying by boltzmann constant. Example: ...
206 views

### Applying rules with functions to expressions with derivatives

I have a function that I want to see applied, potentially within a derivative. The use of delayed vs. non-delayed rules seems irrelevant. See the following: ...
106 views

### How to define a function of z[bar], etc

Using Displaying index as subscript on output: e.g. C[i] -> C_i with Notation[...] or Interpretation[..]? I have often ended up wanting to define functions of annotated variables to better match my ...
342 views

### Transcendental equation Non-linear how to solve [closed]

I am trying to solve the following NON linear system: ...
89 views

### Matrix generation

I have a $2x2$ matrix $M$. $M$ has the following form: M = {{a, bExp[-2ikz]}, {bExp[2ikz], a}} $a, b, k - const.$ z is ...
128 views

### Getting output in the same way as most Stat packages

I have been looking at several of the timeseries functions in mathematica, however running a process like ARDL, ARMA, GARCH or ARCH you would be able to get a ANOVA table, with its coefficients and p ...
270 views

### NDSolve and memory usage

After some googling, i've found similar problems around, but didn't find a 100% satisfactory answer, so let me ask here: I'd like to solve a 1+1 problem using the method of lines. In spherical ...
209 views

### How to declare a function that uses local variables of a module outside this module?

I have the following code Module[{f,x=0}, f[t_] := x + t; ..........; ...f[1]...; ..........; ] My aim is to put the declaration of the function ...
398 views

### Labelling of multiple BarChart elements with “Stacked” layout

I am trying to create a stacked BarChart where each BarChart has different ChartLabels. ...
179 views

### Verify Harmonic Addition Theorem with Mathematica

I've calculated the harmonic addition theorem and would just like to check my result with Mathematica. However, ...
170 views

### Taking a percentage of data from a list or a table

I have a list of data and for the calculation I only need the a of portion of the data. I know that Take[data, {1,100}], for example, is taking line 1 to 100 of the ...
201 views

### Parallelizing or optimizing a script for calculating the size of all pairwise intersections between collections of sets

I need to speed up or parallelize an operation that looks essentially like this: ...
258 views

### Quickly reducing the number of decimal digits for a set of real numbers

How can I quickly convert a number with $n$ decimal points to a number of with $m$ decimal points? Round works, however, it is slower than I would like. This ...
138 views

### Remove braces, {}, from around DynamicModule output?

Is there a way to remove the braces from the front end output associated with DynamicModule? For instance: ...
985 views

### Reconstruct text pages cut by shredder

Q1: I have a page of printed text file, but it was cut by a paper shredder (from top to bottom). You can download all the paper fragment here. There are some examples of them. How can I reconstruct ...
343 views

### Plotting the direction field of a differential equation

I have to sketch the direction field for the following differential equation: $$\frac{dy}{dx}=\frac{-0.02 y +0.00002 xy}{0.08 x-0.001xy}$$ This is the code I used, which gives an incorrect plot: ...