2
votes
2answers
85 views

`PrimeNu` counting function

Building on this question, what is the most efficient counting function for distinct prime factors? It would obviously be more efficient if Prime and ...
6
votes
1answer
316 views

Maple like collect command in Mathematica

In Maple I often simplify expressions for functions of same argument using the collect command: > collect(a*f(x)+f(y)+x*f(x), f, factor) (a+x)*f(x)+f(y) where ...
1
vote
1answer
84 views

Asymptotics of sum of binomials

I would like to find the asymptotics of Sum[Binomial[n,i]*1/i^((n+1)/2),{i,1,n}] I saw Find asymptotics of Sum[2^i*Binomial[n-i-1,2*n/3-1],{i,0,n/3}] but I ...
1
vote
1answer
165 views

Problem to solve an integral equation [closed]

I am new to Mathematica. I am trying to numerically solve for C in the following equation: $\begin{equation} \begin{array}{lcl} -\int_0^\infty (5000000+100000 x+ C)^{-1} ...
1
vote
2answers
97 views

Identify / change working directory for the InstallableNET runtime

I am currently attempting to use .NET/link to call a third party DLL from Mathematica using DLLDefinedFunction. I have been able to link against and call many of ...
3
votes
0answers
78 views

Understanding NDSolve::ndsz

I'm working on a largeish system of differential equations where I encounter the NDSolve::ndsz step size is effectively zero; singularity or stiff system suspected ...
6
votes
3answers
257 views

Loop function over list [duplicate]

I would like to divide element 1 of a list by element 2; element 2 by element 3, and so on. What is the best way of doing this? I have tried f = #1/#2 & ...
2
votes
1answer
119 views

Solving Complex Equation Over Reals

I want to solve the equation $\frac{abi}{a+bi}=4-2i$, where $a$ and $b$ are real numbers. I know from hand-solving the answer is $a=5$, $b=-10$. How do I get Mathematica to tell me this? I tried: ...
4
votes
1answer
142 views

Exporting images in a Mathematica array to a PDF s.t. each image is precisely $n \times m$ millimeter in dimension [duplicate]

I have a number of images in a Mathematica array, and I'd like to export the images to a PDF s.t. each image is precisely scaled to be $n \times m$ millimeters in dimension. The idea is that printing ...
4
votes
2answers
196 views

Is it possible to `Protect` a dynamic programming process?

I wrote a function using dynamic programming to speed up the evaluation. For safety, I also want to protect this function. Take factorial for example: ...
1
vote
1answer
59 views

How to get the time when a notebook is saved and closed

I want to get the time when a notebook is created and the time when the notebook is saved and closed, that is to say, the whole time when a notebook exist. What should I do? Thank you!
2
votes
1answer
299 views

Resonance Curve using NDSolve

I am trying to make a resonance curve like this one below, using NDSolve. I tried to use code as below. Basically I try to hold solution for a w (driving frequency value) using NumericQ and then ...
4
votes
1answer
170 views

How to get an equivalent of WeightedData in Mathematica 8?

Is there an equivalent command of WeightedData (new in version 9) in Mathematica 8 or I have to define it by myself? I haven't found anything in the site or ...
5
votes
0answers
195 views

Units: Custom-defined units possible?

Converting between revolutions per minute (RPM) and revolutions per second (RPS) is not straightforward for me in Mathematica. I know that $1\; \text{RPM} = \frac{2\; \times\; \Pi\; ...
0
votes
0answers
227 views

Solving for equilibrium distribution (symbolic) by matrix multiplication

I have a huge transition matrix (81x81). The matrix is too huge to paste here, so I store it in this notebook. (There are constraints on the symbols: $0<p_b<1$ and $0<p_g<1$. If further ...
23
votes
4answers
3k views

How to create effect like Van Gogh's stroke brush?

I need to apply Van Gogh's stroke brush effect to a random image Take the following image as an example: Thank you so much if you could help!
0
votes
0answers
131 views

Making a predictive statistical model

I am totally new to Mathematica, and I have never used a similar program, apart from perhaps Excel (and I didn't even use Excel on a professional level). So I want to create a mathematical model ...
1
vote
1answer
170 views

How should I go about writing more functional and list based code? [duplicate]

I've heard that Mathematica is usually faster when the code is list-based and/or uses a functional paradigm. I'm still working on getting the hang of this; there are a lot of ...
1
vote
1answer
189 views

How do I construct a non-linear model from experimental data?

I want to find a function $w=f(x,y,z)$ that fits experimentally determined values of w. For example, assume ...
2
votes
2answers
130 views

Deleting elements on a list by the first element of another list

I was trying to make this L1 = {{2, 1}, {6, 4}, {8, 7}, {9, 5}}; L2 = {{2, 9}, {9, 6}}; L = Union[L2 , L1] And I used this: ...
1
vote
1answer
74 views

Defining functions that reference other values

How could I define a function that references other values? eg a = 2 x; b = 4 k; f[k_, x_] := a^b
0
votes
1answer
196 views

Is it possible to convert expressions containing Root objects to Excel formulas?

I am still a beginner and do not fully understand pure functions and root objects. When I tried to calculate the inverse of a function, Mathematica gave me: ...
5
votes
0answers
1k views

Threads vs Cores: How many kernels need to launch in parallel Mathematica?

I have a dual-core intel machine. I would like to test how many parallel local kernels should be launch to get the optimized performance. Knowing that the HyperThreading technology of Intel could run ...
2
votes
1answer
81 views

Need to run evaluation 2 times

Why does this only work after running the evaluation 2 times? ...
4
votes
1answer
378 views

Edit Plot/Graphics after it's been drawn. [duplicate]

Sometimes I run into a situation when there are graphics objects (mostly plots) that take a while to draw. Good practice would suggest you do all your evaluation outside ...
3
votes
1answer
253 views

How to simplify to form without imaginary unit

I have an integral that I compute with Mathematica and as a result I get a seemingly complex expression (i.e. the expression contains the imaginary unit, $i$, at some places). However, if I try to ...
5
votes
4answers
430 views

A fast way to compute arrays avoiding If or Which

I found out that if I have to calculate huge arrays with most of the elements being zero( let's say each row has 10000 elements and only 8 are non zero) and the non zero elements' positions being ...
1
vote
0answers
36 views

Internals of Prime function [duplicate]

Does anyone knows how exactly Prime works ? For example how Prime[1000000000] is calculated ? The only information I found was ...
1
vote
1answer
91 views

ctags for Mathematica files?

I alway use vi to edit Fortran files. I can use ctags to know which variables and functions I have already defined. Now I use vi to edit Mathematica *.m files. I tried to use ctags for *.m files, but ...
1
vote
1answer
124 views

MAP a business cycles model

There is a Business Cycles Map on Phaser 3.0 and I've trying to run it on Mathematica the last four days without succes. The equations are $$ x_1 = (1.0 - a s)x_1 + a \left[s m + g \left(\frac{s ...
1
vote
0answers
73 views

How can I control the size of exported image in HTML code under certain magnification value?

I've inserted a picture in one cell, however, when I exported the cell as HTML, the size of my image in the html tag was doubled(the image file in HTMLFiles was the same as the original image). I ...
6
votes
0answers
157 views

Issue with FindCurvePath

I have a problem with the function FindCurvePath. In some cases it crashes the Mathematica 9 Kernel. Here an example, where it crashes the kernel: ...
6
votes
2answers
2k views

How to convert a string of number into real numbers without precision loss

I searched and did not find similar answers which can resolve the 'no precision loss' issue. A sample string is: ...
6
votes
3answers
392 views

Mapping a function that assigns values to a list over a different list

I'm trying to get used to Mathematica's approach to programming and list manipulation, and am struggling with one thing. Say that I have a function f which takes a ...
2
votes
2answers
87 views

Forcing RecurrenceTable + NIntegrate to evaluate lazily

I have a recurrence relation that grows exponentially if expressed in closed-form. I need to integrate this function. If I plot it, I think Mathematica evaluates the recurrence numerically at every ...
1
vote
0answers
261 views

Slow Open Dialog user Interface in Mac OSX Mavericks

The other day I noticed an interesting problem with Mathematica on the Mac. When I'm in the Mathematica application and try to open a mathematica file with the "Open" option of the file menu the open ...
0
votes
1answer
105 views

Pure function in Nest

I can't figure out what I'm doing wrong here: Table[Nest[# + 0.1 * -i * #^2 &, 2, 1] , {i, 0, 0.5, 0.1}] (* {2., 1.96, 1.92, 1.88, 1.84, 1.8} *) The problem ...
1
vote
1answer
324 views

dynamically set fit parameters and models with FindFit

I want to fit a gaussian profile by setting some values dynamically, but FindFit returns an error and i can't see the problem. with a given gaussian: ...
2
votes
0answers
62 views

Georeferenced bitmaps

The command Export["filename.jpg", graphic] will export the graphic object graphic to the file ...
2
votes
2answers
308 views

Can Mathematica identify formulae or sequences of numbers?

Can Mathematica suggest what a formula means? For example if I input $$\sum_{i=0}^n i$$ can it infer that this is a sum of integer values from $0$ to $n$? Or if I enter $0,1,1,2,3,5,8,13$, can ...
-1
votes
1answer
112 views

Button with for loop

How can I call a function that has a for loop inside a button? If I just write button[{"name", function[]}] nothing happens.
14
votes
2answers
482 views

How to simulate the true reflective movement of a particle bouncing around in an ellipse?

Please help me to simulate the movement of a particle inside a region with elliptical walls such that particle is reflected from the walls and continues to move. A friend was able write code to ...
0
votes
3answers
445 views

Plotting Voxel in mathematica

I am developping a 3D reconstruction application. I recuperate the voxels coordinates (the coordinate of each voxel) of the object that I need to reconstruct. Each voxel have a dimensions like this ...
1
vote
1answer
314 views

Feynrules -> FeynArts issue

When I try to use model files generated by FeynRules in FeynArts, I always get errors of this form Coupling definition in ...
4
votes
3answers
356 views

First 10 digits of $\pi$ without rounding

I need to have $\pi$ with an accuracy of $10$ digits. My first guess would be N[Pi, 10] However, this rounds to the last digit instead of just chopping of any ...
10
votes
4answers
294 views

No response to an infinite limit

Trying to compute this limit, things seem to get frozen, even for hours. What would you recommend to fastly compute it? ...
1
vote
1answer
1k views

How to find the area between two curves

Find the area between y = 1 - x/π and y = Sin[x]. Here is what I have typed in so far into Mathematica: ...
1
vote
1answer
123 views

Specify positions in a SparseArray using patterns with functions

I spent some time trying to figure out what was what was making so slow the calculation of the following array(actually this is only a SUPERsimple toy model): Input to the array: ...
4
votes
3answers
213 views

How to compile a diagonal array efficiently?

For example, if we use some functions defined prior to Compile, we usually have the main evaluators in the compiled codes, pointing to the definition of the ...
1
vote
1answer
85 views

Multilpe matrix (mxm) and vector (n), wich are unequal, so get a (three dimensional matrix) mxmxn matrix

For example I have this matrix: mk = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}} and I'd like it to multiple with this: ...

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