# All Questions

0answers
467 views

### Solar system simulation (n-body physics) with OpenCL

I would like to simulate a n-body solar system in Mathematica. I have found the following example: ...
9answers
918 views

### How to replace an element in a list based on the value of the next element?

I use Mathematica a little bit. I try to understand it, but it is hard I have a list of 5 numbers selected randomly from 0 and -1. I have to replace a 0 with a 1 when the 0 is followed by -1. My ...
3answers
200 views

### Prime factor counting function

Is there any way I can speed up this prime factor counting function? (I am looking for all numbers in a range with 3 prime factors (counted with multiplicity).) ...
1answer
148 views

### Does Mathematica know if an integral is convergent or not?

Consider the following integrals that I asked Mathematica to do, ...
3answers
513 views

### Different results for integration using Mathematica and MATLAB

I have the following integration: $$\text{y}=2 \sqrt{\frac{1}{\pi }} \int_0^{\infty } \frac{e^{-z} \left(1-e^{-\frac{z}{b}} \left(\frac{a}{a+c z}\right)^L\right)}{\sqrt{z}} \, dz$$ I get different ...
2answers
135 views

### How to calculate expected return, row by row in matrix? [closed]

Please help me, I'm writing my project and dont know how to solve this big matrix: I have to compute return row by row: 1st row: (18.32-17.14)/17.14 ; (19.17-18.32)/18.32 .... ...
1answer
144 views

### Efficient ways to rotate a ListPlot?

I have a numerical solution from a differential equation that is in the form of a list, in $(x,z)$-plane. I would like to rotate the 2D ListPlot around the $z$-axis ...
3answers
244 views

### Finding the square root of a squared number?

Taking the square root of the square of a number Variable set to a real value I'm wondering why these examples a = -4.3; Sqrt@a² Sqrt@(a^2) Sqrt[a^2] Sqrt[a²] ...
4answers
230 views

### Unexpected dots from Line

I have noticed cases where Line produces dots in a graphics object when I think it shouldn't. The first of these is: ...
0answers
90 views

### Reading Eigenvalue / Eigenfunction result from Reduce

I am trying to find the eigenvalue/eigenfunction solution to: $$\tag 1 y''+3y + \lambda y=0 ; y'(0)=0, y'(\pi)=0$$ I used DSolve and Reduce and they seem to converge, however (embarrassingly) I am ...
2answers
64 views

### Pattern-rewriting Pattern triggers error?

I am trying to rewrite patterns. For example, I'd like to rewrite the pattern jFoo_Integer which has FullForm ...
1answer
81 views

### Assign clipboard object in mathematica when print screen is pressed (windows)

Mathematica runs behind, while another window is selected. When I press print screen, I want mathematica too detect this and call a function with the picture as argument. ...
2answers
153 views

### Pulling out common terms when simplifying complicated equations

I have a complicated expression where common terms are apparent but Simplify[] and FullSimplify[] don't appear able, even with plenty of assumptions added, to reduce down to a simpler form with common ...
1answer
207 views

### Summation with jump indices like 1,4,6,9?

I is easy to enter $\sum_{s=1}^{n}k(s)$ But how can I enter $\sum_{s=1,3}k(s)$ ? When I try it, Mathematica says ...
0answers
105 views

### Manipulating the pitch of a sound

After reading Manipulating a continuous stream of sounds I have to ask about controlling the frequency of a Sin sound in a continuous manner, with a ...
1answer
135 views

### Ordinary differential equation invloving the function composition

I want to solve the following function: DSolve[(A1*Exp[B1*f[x]] + A2*Exp[B2*f[x]])*f'[x] == A1*Exp[B1*x] + A2*Exp[B2*x], f[x], x] And this is what I get as an ...
0answers
92 views

### Assigning the answer of Solve to a variable [duplicate]

If I enter Solve[(x-2)(x+2)==0,x] then the answer comes up as {{x -> 2}, {x -> -2}} I want to make two variables ...
3answers
161 views

### PlotStyle with Table

I want to create a plot style with a table and manipulate the variables in the plot style. ...
1answer
117 views

### Simplify doesn't simplify HypergeometricPFQ with exact arguments

Consider a series: $$\sum_{t=0}^\infty \frac{8^{-11-2t}(22+4t)!}{t!(11+t)!(11+2t)!(32+t)}$$ ...
0answers
152 views

### How to get vertices of a polytope given by equalities and inequalities?

I have a polytope given by some equalities and inequalities, how can I get all the vertices of the polytope? If there's a way to deal with the one given by inequalities only, how can I reduce the ...
1answer
92 views

### How to start Mathematica kernel without loading init.m?

Is it possible to start Mathematica kernel from UNIX command line without having the init.m loaded, but not by simply deleting or commenting out it before hand? If this is a Mathematica script, is it ...
0answers
86 views

### Problem with strings imported from PDFs

I am currently working with a list containing around 20 strings which contain around 30,000 characters each. The strings are imported from PDFs and the list containing all the strings is assigned to a ...
1answer
150 views

### How to create a plot of the volume between three surfaces

I need help creating a plot that I can manipulate the variables for the volume between three surfaces. I am trying to make it look like this example here: ...
1answer
288 views

### How to constrain memory usage on HPC?

I found the performance of built-in function MemoryConstrained is very poor. It stops the evaluation after the memory limit has already been exceeded greatly than ...
0answers
64 views

### Fitting data set with series expansion

I have a function given in a form of a list: ScalarField={{$\epsilon$,$y_1$},..{1,$y_{3000}$}} It is defined in the range $(\epsilon,1)$ (spacing between grid points is homogeneous), where ...
1answer
82 views

### Transpose a ragged triangular matrix and display as columns rather than rows

I have a triangular list of lists as follows: ...
0answers
67 views

### Widget - GUI help

I was wondering if someone could explain me the code written below (example File Dialog from mathematica). Especially the part with returnValueand ...
3answers
160 views

### Pure function inside another pure function

I have the following working expression: In[15]:= Length[Select[IntegerPartitions[10],First[#1]==5&]] Out[15]= 7 But, instead of using the constant 5 I want ...
3answers
322 views

### How to get back name of the number from Max function? [duplicate]

So I have this question, using a toy example: a={1,"this"}; b={2,"that"}; result=Max[0,a[[1]],b[[1]]] the result will be 2. However what I want to obtain is ...
0answers
63 views

### Rearrange cells without cut-paste

When working in a Mathematica notebook, I often want to reorder cells. Most of the time, I am adding cells at the bottom of the notebook, until I realize it may be better to insert this calculation at ...
1answer
103 views

### NDSolve`ImplicitRungeKuttaGaussCoefficients doesn't work

I am using Mathematica 9.0 on Ubuntu. I tried the first example from this documentation page, but it returns unevaluated: ...
1answer
90 views

### Is there really a bug in the following code, taken from the reference documentation for PetersenGraph?

PetersenGraph[5, 2, EdgeLabels -> {8 \[UndirectedEdge] 9 -> "hello"}] appears to evaluate perfectly, as expected, but in my version 9.0.1.0, the option ...
1answer
457 views

### How to map an image to get an illusion of 3D

I would like to distort or map a given jpg so it looks 3D as in the following youtube video: http://www.youtube.com/watch?v=IfCCUd8mFtg. I usually use conformal mapping (a complex function) to do my ...
1answer
102 views

### Aborting from inside a ScheduledTask

If you have an Abort[] inside a ScheduledTask expression, what does it abort? The scheduled task evaluation, or any main kernel ...
1answer
70 views

### Trouble avoiding computation in DynamicModule when input field is not defined [duplicate]

I'm having trouble detecting when my InputForm supplied String variable has a value. After looking at: How to compute values only if input fields are filled? I tried a StringQ test: ...
1answer
147 views

### Run kernel script in cygwin without window popping up

I'm calling mathematica scripts running kernels through a cygwin terminal, which are again executed from c++ code. When I do this a window pops up, prints warnings and errors if there are any, and ...
1answer
94 views

### Manual CellGrouping option causes crash at cell evaluation

Update: Try to reproduce this behaviour with CellGrouping set to manual. To do that: either evaluate ...
2answers
125 views

### NIntegrate using Boole doesn't work

This doesn't want to work for me - I don't know why not. It usually gives me 0, but sometimes also a different number. I know it should be a small, non-zero number. ...
1answer
125 views

### Solve returns a wrong answer

I'm afraid the following is rather localized questions, but I don't know how to simplify and generalize it. I have the following two points (in the real plane): ...
2answers
126 views

### Can one use Map during Expand?

Can one Map a simplifying function to the summands of an Expand before fully expanding the expression in question first? ...
3answers
250 views

### How can I calculate a combination of limit and sum?

How can I solve the above problem? I enter it as: Limit[Sum[Sqrt[1 + i^2/n^2]/n, {i, n}], n -> Infinity] but this is not working:
1answer
202 views

### How to graph in Cylindrical coordinates in 3D

I need help figuring out how to plot in cylindrical coordinates. I read that CylindricalPlot3D was replaced with ...
1answer
166 views

### Custom image as plot marker

Is there a quick and easy way with Graphics to replace the standard data points in a plot with a custom image?
2answers
125 views

### Arrowhead as MeshStyle or PlotMarkers for ListLinePlot

Is it possible to use the Meshstyle option of the PlotMarkers option in ListLinePlot to have ...
1answer
101 views

### Shortcut to insert plaintext?

Oftentimes I would find it useful to insert plaintext, to not be evaluated as input, right next to my input code. Is there a shortcut key to insert such a plaintext input box? I have relied on ...
1answer
78 views

### How to find coordinates of an abstract vector relative to a basis

Let's say I have a degree 3 homogeneous polynomial over variables $x0, x1, x2.$ There are then 10 distinct monic monomials, forming a basis of the vector space of polynomials of degree 3. If I have ...
1answer
231 views

### How to type binomial coefficient $\binom{n}{k}$

I know how to type a fraction as you would write a fraction in Mathematica (9). How do you type Binomial[n,k] as $\binom{n}{k}$ in Mathematica? Is there a single ...
2answers
112 views

### Plot with sum and binomial command

A few days ago I asked about a problem with plotting a sum. You advise me to use Evaluate option, and that helped me very. But now I have a very similar problem, but i can't find the mistake. I have a ...
0answers
36 views

### up arrow works in math version 9, fails in math version 8 ^[[A [duplicate]

I have strange up-arrow behavior on command line Mathematica 8 versus Mathematica 9. Version 9 gives me history, where version 8 fails with escape codes. Any way to make them both work on the same ...
10answers
512 views

### How to pick increasing numbers from the list

How to pick increasing numbers from the list. lst = {5, 3, 6, 2, 7, 4, 8}; out: {5,6,7,8} So many interesting ...

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