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
919 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
191 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
231 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
740 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
318 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
83 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
187 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
963 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
133 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
466 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
871 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 ...
3
votes
2answers
141 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
281 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 ...
3
votes
3answers
293 views

Removing non-word characters from a string

I'm trying to get a list of words from a string. Sounds like an easy task for Mathematica. I have the following code: ...
3
votes
1answer
103 views

Alternate controls in manipulate

Is there a way to have two controls that govern a single variable in a Manipulate? Specifically, I am using a Locator to select an {x,y} coordinate, but I would also like the user to be able to ...
0
votes
1answer
96 views

Summing Multinormal Distributions

So, I'll explain the problem first. I have two populations that have values for two different channels (c1,c2). I've modeled these using MultinormalDistribution[]. I would like to add some noise to ...
1
vote
2answers
82 views

Extract the real components from a very large expression

Suppose I have a very long expression (>500,000 characters) which contains a mixture of real and imaginary terms. e.g ...
1
vote
3answers
130 views

Where Statement

Is there a "parallel" way to perform these operations? Indices = {} For[i = 1, i <= Length[w], i++, If[w[[i]] < 0, AppendTo[Indices, i]]] Which gives a ...
3
votes
2answers
136 views

How to convert multidimensional matrix into regular matrix?

I have this multidimensional matrix: {{{{a1, a2}, {a3, a4}}, {{b1, b2}, {b3, b4}}}, {{{c1, c2}, {c3, c4}}, {{d1, d2}, {d3, d4}}}} I would like to convert it into ...
11
votes
1answer
378 views

Multiplayer game in Mathematica: how to communicate between kernels?

This may have been asked already, but I am considering making a game in Mathematica that two people can play. However, the issue with my idea is that the other player can't view the cards of the first ...
0
votes
0answers
89 views

My plot is cut off if a frametick is “0” but resized if a frametick is “0.” Why?

I have been trying to customize the frame ticks and frame label around a certain contour plot and am running into very strange behavior where the graphics will get cut off by ...
5
votes
1answer
135 views

Finding minimum fly-by radius between Mars and spacecraft from interpolating function

I've written an interplanetary trajectory solver/plotter that plots the path taken by a spacecraft on an Earth-Mars mission, but have run into a little trouble when the spacecraft actually reaches ...
0
votes
1answer
94 views

Decompose Expression into Segments

Say I have an expression test = 3 x1^2 - 2 x3^-3 and I would like to decompose the expression into {3 x1^2, -(2/x3^3)}, I can do ...
1
vote
2answers
114 views

How to work with lists of functions

I have some lists of interpolated functions and I want to know if there is an easy way to operate with them. A simplified example: ...
2
votes
2answers
780 views

Using the epsilon tensor in Mathematica

I'm having a great deal of trouble getting started on a weekly homework assignment in Mathematica. The assignment requires we use the epsilon tensor which is apparently built into Mathematica as ...
1
vote
1answer
68 views

Integral not being evaluated

I'm trying to do the following integral, but Mathematica won't evaluate it - it just spits out the actual symbolic integral. $$\frac{e^{-\frac{(k-d)^2}{2 a^2}} \left | \frac{-d+\frac{c ...
0
votes
1answer
68 views

Plot Natural Log and Derivative Help

h[x_] := Log[2 x + xSin[x]] h'[x_] := (2 + Sin[x] + xCos[x])/(2 x + xSin[x]) Plot[{h[x], h'[x]}, {x, 0, 10}] Whenever I try to plot these two functions the plot ...
0
votes
1answer
214 views

Importing data to make a DateListPlot

I am having a hard time trying to import some text data for later use in DateListPlot. My first field in my data is a date of the format "yyyymmdd". I tried to ...
0
votes
0answers
176 views

Speeding up inversion of symbolic matrices by invoking caching

Is it possible to reduce the computation time taken to find inverse of symbolic matrices USING CACHING TECHNIQUES accessible (if any)? I am trying to compute inverse of symbolic matrices of size ...
1
vote
2answers
635 views

Why do Solve, NSolve, and FindRoot all fail on this simple, solvable actuarial equation?

If we express conditional mortality as a vector of annual probabilities of death, like so ...
1
vote
1answer
79 views

Do I need to clear all definitions whenever I experiment with new parameter values?

Do I have to clear all my definitions whenever I experiment with different parameter values for my model? For example, I have a simple model as follows: ...

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