0
votes
0answers
98 views

How to modify the file “KeyEventTranslations.tr” to use Enter to evaluate the current cell? [duplicate]

I asked the following question before, but I do not think it has been fully answered. By default, we use Shift+Enter to evaluate the current cell, and use Enter to get a new line. Is there a way ...
4
votes
0answers
92 views

Converting problem into form involving Probability

I want to solve the following problem symbolically, using Probability: What is the probability of the first random variate of a set to be present more than ...
2
votes
1answer
111 views

RSolve: Errors while solving Partial Difference Equation

I tried solving following partial difference equation in Mathematica by typing ...
2
votes
2answers
600 views

Convert list to sequence

I was just thinking how Tuples was created so , I came up with this, ...
3
votes
3answers
169 views

Performance on Multinomial Deviate is slow

Most of the time in my program is spent on this single line of code: out = RandomVariate[MultinomialDistribution[nt, tmp]]; ...
11
votes
3answers
212 views

Head of a MatrixForm expression?

An example in http://www-zeuthen.desy.de/theory/capp2005/Course/hahn/mathematica.pdf amounts to the following ...
1
vote
2answers
151 views

Factorization of a list with composite integers to a combined list of all prime factors

The following function io[aIn_] produces a list bOut containing ALL the prime factors of an Integer via the standard function FactorInteger[]. My code is: ...
2
votes
0answers
375 views

Speeding up Nonlinearmodelfit by constraining parameters?

I have a complicated parametric PDE that can be fitted to some data with NonlinearModelFit, but takes several hours to estimate the best values of the four free parameters. Currently, the code ...
1
vote
2answers
222 views

Manipulating sparse array elements

Suppose I have two sparse arrays ...
1
vote
1answer
444 views

NIntegrate(with singularities) gives different results, which one should I trust?

I am doing an Numerical integral with sigularities. ...
11
votes
5answers
2k views

What is the fastest way to extract a substring from a huge string?

I develop an algorithm to find the most common substrings of a given length n up to a certain distance l in front of a pattern p in a huge sequence S. E.g. I want to find the most common hexamers ...
2
votes
1answer
160 views

Resizing palettes

My eyes are weary and my sight grows dim, so I used the zoom control bottom-right in the palette. Unfortunately, having zoomed in the palette window cannot be resized - so I can't see the rhs - and ...
2
votes
0answers
47 views

Limiting scope of Front end “Replace All” in Find & Replace

The warning on find and replace isn't explicit and I only found out after an almost harmless global change that I really was replacing ALL, not just all instance in my selection (which is where most ...
0
votes
0answers
77 views

NMaximize issue and regularization

I want to maximize over the space (output of NDSolve, in appendix to the question) but I do not think this is strictly important in this case), to get the maxima of the solution as a function of time: ...
6
votes
3answers
262 views

Enumerate the 1-factors (perfect matchings) of $K_n$

Introduction I would like to enumerate the 1-factors, or (near-)perfect matchings, of the complete graph Kn. The adjacency list representation for Kn is basically { (x, y) | 1 ≤ x < y ≤ n }. For ...
0
votes
2answers
166 views

Selecting index position of data from a table that is less than a certain value

I have a table of numbers with a few thousand entries, and I'm trying to find the first index that is less than a particular value. An example of the table I'm working on is as follows: ...
6
votes
2answers
476 views

How can I define a 3d-body through different views? [closed]

In one of the maths blogs I follow I stumbled upon the following question: The bottom, side, and front views of an object are shown below: How would the object look in three dimensions? My ...
1
vote
0answers
81 views

How to make noncommutative multiplication agree with commutative multiplication

I need a noncommutative multiplication that is Associative Distributive $A**0=0$, $A**1=A$ Agrees with the commutative multiplication ($A**(k B)=(k A)**B=k (A**B)$) I have found a code ...
1
vote
0answers
34 views

Integration of any interpolation generates invalid comparison errors [duplicate]

Integrating a simple interpolated function as follows generates invalid comparison errors. ...
12
votes
2answers
915 views

Find the eigenvector associated with the smallest eigenvalue, not smallest in magnitude

I am trying to find the eigenvector of a $20000 \times 20000$ sparse matrix associated with the smallest eigenvalue. I realized that the smallest eigenvalue might be negative; for example, if the ...
0
votes
3answers
190 views

Padding of matrix

I want to do padding of matrix a = {{x,x},{x,u}}; to ...
0
votes
1answer
156 views

How can I obtain more significant digits? [duplicate]

I type f1[x_] := 12 x^5 - 975 x^4 + 28000 x^3 - 345000 x^2 + 1800000 x N[f1[15.5], 15] and obtain 3.74112*10^6 BUT It´s not true!!! the result is larger than ...
2
votes
1answer
71 views

How to put Labels in of a list of number in a chart?

I can´t put the labels 0,....,31 in this simple chart on the usual place, or better just over the Top of each bar How should I do? ...
0
votes
2answers
110 views

Finding lags of time series with `Do`

I have generated two time series, S[t] and P[t] as follows: ...
2
votes
2answers
132 views

Counting Events in a moving date range

I want to count the number of times events take place in a date range. The counting is done over a window of e.g. 28 days where the goal is to have between 11 and 13 events in the time window. The ...
5
votes
2answers
168 views

Using StringCases and treating certain phrases as single words

My question is about StringCases. When I use this function, each word is separated by a ,. But I want some noun phrases like ...
5
votes
2answers
105 views

How to robustly apply ToBoxes to a Dynamic expression?

Inserting a Dynamic object in a boxform expression messes up syntax colouring. See the following example. where the variable ...
5
votes
1answer
230 views

How to embed a movie into a Mathematica-made presentation?

The question is completely formulated in the title. However, to make it more presize, I am making presentations for lectures. The presentations are done in Mma. I have some illustrative material to ...
5
votes
2answers
193 views

Join lists of lists with unique id

Sorry for the vague title, but I can't describe my problem properly and shortly. I am maintaining a list of players and their games with the following form: ...
1
vote
1answer
735 views

Collecting lists using Reap/Sow

I have a list like {{a,x},{b,y},{c,x},{d,z},{e,y}} and would like to produce from it a list formed by collecting all top-level elements whose second components are ...
5
votes
1answer
195 views

Is there a site where you can run mathematica without having to download anything?

I made a project in mathematica, and I have to present it in front of a couple of layman in two days, but I have to use school laptops and for some stupid reason I am not allowed to download anything ...
0
votes
1answer
316 views

Nonlinear fit with piecewise functions

I have an ensemble of data points $(x_i,y_i)$ and I need to fit them according to $y=F(a,b,x)$ if $x \leq x_{ref}$ and $y=G(c,d,x)$ if $x \geq x_{ref}$. The parameters I need to adjust are then ...
1
vote
0answers
151 views

How can I add drop shadows to the text of non-input/output cells?

Inspired by simon woods's wonderful shadow function, I want to add drop shadows to all the text of non-input/output cells in a notebook, something like this: By using simon woods's shadow function, ...
0
votes
0answers
82 views

An error message with NIntegrate and inability to plot the integrand

I took a function of x which depended on parameters on m,n,a,y and then first summed up the n from -Infinity to Infinity and then I set the other parameters to some random values and then I asked it ...
2
votes
1answer
186 views

Speed up Select on large list

I am running this on a very large list, it is important to notice that some times the dates in v occure several times, and I want the selected list to show the same amount. This produces the right ...
19
votes
1answer
958 views

Web Browser Screen Shot

I have Safari, Opera, Chrome, Firefox and IE installed how might a get a browser screen shot of a set of HTML code from inside Mathematica(for any of those browsers)? (Image is optional) The ...
0
votes
0answers
59 views

Given a list of pairs, average the second elements of pairs whose first elements match [duplicate]

Say this is my list: mylist={{1,4},{1,6},{1,11},{2,12},{2,14}} I want to do an operation that looks at the first element of each pairs, and for all those that ...
1
vote
1answer
131 views

How to convolve a Unit function (like “UnitTriangle”) with a InterpolatedFunction

Recently discovered what InterpolatingFunction's are in Mathematica...really amazing/useful. As I understand it, it's basically a curve fitter....sorta. So how ...
4
votes
2answers
132 views

How to model shocks to parameter in a dynamic system?

My simple model is: m[t_] := m[t] = m[t - 1]*p + 2 m[0] = 0 p = 0.5 I can plot the system as: ...
3
votes
3answers
464 views

Alternatives pattern in a function definition

I thought that I remembered a way to write a function definition using "|", but can't find documentation for it. So for example, I'd want to define: ...
0
votes
1answer
869 views

How to find the inverse a symbolic matrix that Mathematica thinks might be singular

I have a square matrix depending on a parameter "a". When "a" has a numeric value (eg 2.1 * 10 ^ 8) through the inverse function Inverse[] I can invert the matrix. If I write the matrix as a function ...
4
votes
1answer
212 views

Reconciling results from Fourier with those form FourierTransform

I need to use the discrete Fourier transform for function that represented as list of values. I started with an easy task to check my understanding. I tried to get the amplitude values for ...
2
votes
1answer
75 views

How to obtain SliceDistribution or StationaryDistribution for an ItoProcess when it is known to exist?

According to this reference page StationaryDistribution[proc] represents the stationary distribution of the process proc, when it exists. When I define the OrnsteinUhlenbeckProcess by the ...
2
votes
1answer
144 views

How to use some other driving process than the WienerProcess?

According to the following reference page http://reference.wolfram.com/language/ref/ItoProcess.html The driving process dproc can be any process that can be converted to a standard Ito process ...
2
votes
2answers
137 views

Expand Graphics based on all elements

How might I force the following Graphics element to expand to contain the Inset text? ...
0
votes
1answer
280 views

How to label the coordinates of the plotted graph?

How can I label the coordinates of the plotted graph? I want to label the coordinate of $(-1,-1)$. ...
1
vote
2answers
242 views

Symbolic solution of irrational equation

Is there any a nice looking solution to the following equation? eq[x_] := 2 x q1 - 2 q2/x^3 - (4 x^3 q3 - 4 q5/x^5)/(4 Sqrt[x^4 q3 + q4 + q5/x^4]) Better than ...
2
votes
1answer
126 views

NIntegrate Warning / Error Messages

I am doing: NIntegrate[Sin[Exp[(x^4)]], {x, 2, Infinity}, PrecisionGoal -> 12] It prints out a host of warnings, but also shows the results as: ...
4
votes
2answers
151 views

DynamicModule updating unexpectedly

I have cut down a DynamicModule that was updating unexpectedly and found the following behaviour I don' t understand. If I do this I get one random value as expected ...

15 30 50 per page