0
votes
0answers
52 views

Resources/ best practices for exploratory economic theory work

This is a little general, so I will try to make it as specific as possible. I used Mathematica a fair amount to derive and check analytical solutions to problems in theoretical economics. Lots of ...
1
vote
0answers
141 views

Creating a simple interactive app with CDF [closed]

I would like to implement an algorithm I have created using a (free) CDF document as interface. The idea is: The user has to give some input values (maybe through a sort of text box, if possible —a ...
3
votes
0answers
158 views

Memory problem in Mathematica 10

I'm having a problem with memory. I'm doing nonliner fits of several data lists to a system of differential equations. When I evaluate the "Do" cycle the memory grows with the iteration step up to my ...
0
votes
1answer
120 views

Map Elements of a list to be Index of matrix

I have a sublist from Tuples[{1, 2, 3}, 2], say for example L={{1,2},{2,1},{2,2}}, and a 3 x 3 matrix ...
3
votes
3answers
284 views

Matrix containing ellipse

I have to make a matrix which contains elements in an ellipse shaped region, but I need to make ellipse region in such a way that larger axis of ellipse is inclined with angle θ with horizontal. With ...
1
vote
0answers
81 views

Issues with zero frequency component in discrete Fourier transform

I'm having trouble with the Fourier function at the moment. I'm solving a set of differential equations with NDSolve, then need to extract the spectrum associated with the curve below: So i use ...
3
votes
1answer
76 views

Nested list in PairedBarChart

I have a dataset consisting of 2 different parameters (x and y), that are evaluated for 3 different values of parameter ...
5
votes
4answers
400 views

How can I get the number of slots in Function?

Suppose that I define f = Function[#1 + #2]; And I want to define a new function, argsNum, so that it returns a number of ...
3
votes
2answers
66 views

Mathematica automaticly evaluates some cells

Is there a command or a trick to tell Mathematica to not automaticly evaluate some cells? I use the NMinimize function to calculates some coordinates and then use ...
1
vote
1answer
57 views

How to programattically create a hyperlink to a local html file? [closed]

I want to cause a button to open a local html file using the default web browser. When I use: Hyperlink["Play","myfile.html"] Clicking on the link opens the html ...
1
vote
0answers
149 views

Use Runga-Kutta method to solve a system of many ODEs [closed]

For my simulation purpose, I need to solve the following system of DEs using 4th-order Runga-Kutta (RK) method in Mathematica: $$ I_{k,0}'(t) = -\beta_1~I_{k,0}(t) + k~\lambda~ \Theta(t) + \gamma~ ...
4
votes
2answers
100 views

Remove singleton from Interval

I am using operations over Interval and the result of an intersection (or union) contains some singletons. Would it be possible to remove them ? Example: ...
0
votes
1answer
71 views

PolynomialReduce inconsistent results

I was playing around with gröbner basis and s-polynomials and I fell upon the PolynomialReduce, and I was wondering why it gives different results when I move around the polynomials in its second ...
1
vote
2answers
115 views

Display Matrix of values with position [closed]

I want to find the table of values of $x^2 + y^2$ in steps of 1, from $0$ to $5$ for $x$ and $y$, together with the position $(x,y)$: something like this: I can only display the $x^2 + y^2$ value but ...
6
votes
8answers
405 views

Merging lists and adding common elements [duplicate]

I have two 2D arrays where some of the x-values are identical, L={{1,1},{2,2},{3,3}}; J={{0,1},{2,2},{4,4}}; I want to add these lists in the following way ...
1
vote
4answers
110 views

Converting format of list

I have a 2D array, data = {{0,1}, {1,2}, {2,3}}; I would like to convert it such that I get the x- and y-values separately, specifically ...
1
vote
2answers
242 views

How do I plot the differential of this function?

Suppose I have this function: $$z(x,y) = \left| \frac{ \frac{1}{3x +iy} -2x}{iy + \frac{1}{x}} \right| $$ I want the contour plot of $\frac{\partial z}{\partial x}$ with axes $(x,y)$. Tried this ...
0
votes
3answers
108 views

how could I repalce Sqrt[x^2+y^2+z^2] back to r

do a calculation in mathematica r = Sqrt[x^2+y^2+z^2] D[D[E^(I (-k r + t \[Omega]))/r, x], y] but how could I get back to repalce Sqrt[x^2+y^2+z^2] back to r ...
3
votes
2answers
255 views

How to get all leaves from a graph's specific node

Let's say I have this graph (The code to generate the graph is at the end) How can I extract all the leaves comming from, let's say "cluster3"?, i.e. {100, 92, 87, 89} I guess I have to first ...
0
votes
1answer
32 views

Why would this function work only when I make a copy of the variable? [duplicate]

Why would this function work with a copy of the function variable: ...
4
votes
2answers
224 views

Tracing a path on a polar coordinate grid

I attempt to trace the path of a point when shift-dragged on a polar coordinate as shown on the picture below. But I only managed to snap the point to the grid. Insight on how to accomplish this? Any ...
12
votes
2answers
185 views

Possible Bug in DiscretizeRegion with Option MaxCellMeasure

fixed in 10.0.2 Consider the following ImplicitRegion: reg = ImplicitRegion[x^2 + y^2 + z^2 == 16, {x, y, z}]; We can ...
23
votes
2answers
495 views

Why is Query so much slower than Part?

Time for another of these(1),(2) as yet another new-in-10 function appears to have poor performance compared to older alternatives. This time: Query appears to be ...
8
votes
1answer
251 views

Why is Dataset upset by division by zero?

Consider this example: ds = Dataset@Transpose[<|"a" -> {1, 2, 3, 4, 3, 2, 1}, "b" -> {6, 5, 4, 3, 2, 1, 0}|>, AllowedHeads -> All] Now say I ...
0
votes
1answer
87 views

Calculate integral in limit of very large coefficient

How I can calculate following integrals for large values $\alpha$ in Mathematica: $$ I_1 =\int_{0}^{y} \exp\left(\, -\alpha \sqrt{x(1-x)}\,\right)\, {\rm d}x $$ $$ I_2 =\int_{0}^{y} \exp\left(\, ...
2
votes
0answers
90 views

How to make Eigensystem in version 10 produce the same results as version 9 [duplicate]

The Eigensystem in version 10 seems to give slightly different results as in version 9: ...
1
vote
1answer
93 views

How to make a region plot indicating the largest among a set of functions [duplicate]

I want to make a RegionPlot (or possibly a ContourPlot) in $x$-$y$ space that indicates which among a set of functions is the ...
1
vote
1answer
95 views

Whats the most efficient way to solve an equation numericaly (because it has no analitical solution)

So, I think the problem that Im having is simple but, still, Im not sure on how to do it. I have an equation with no analitical solution: $a_1 \sin \left(2 \theta \right)+a_2 \sin \left(2 ...
2
votes
1answer
118 views

How to generate specific function using BSpline command/

I want to generate an approximation function that fits a curve to points. My goal is to obtain an actual formula. Is this possible with the BSpline function? Using the following code: ...
0
votes
0answers
37 views

Scoping in recursive function leading to unexpected results

I'm trying to implement Ramer-Douglas-Peucker line simplification in Mathematica, and I'm running into an issue with recursion. My implementation of the algorithm is below: ...
6
votes
4answers
289 views

Using ListPlot and Joined, how to keep markers in colour but make all joining lines gray?

I want to create a ListPlot with three sets of data, where the data in each set are joined by a line. This is an example: ...
2
votes
0answers
112 views

Edge finite elements in Mathematica [closed]

I am wondering if it's possible to extend the Finite Element capabilities of Mathematica so as to include other types of elements such as edge vector elements (Nedelec) which can be used in ...
3
votes
1answer
144 views

How to dequantify units in mathematica?

Is there a function which applied to a quantity returns its numerical value so I for instance can fill it into my Predictorfunction?
2
votes
2answers
116 views

Image Processing: Using AdjacentBorders with SelectComponents

I've been doing some image processing and have been having trouble with the AdjacentBorder command. I've got an image in which I have several elements that are on ...
3
votes
3answers
224 views

How to combine a plot with an image

I have an external data file data which contains the position of stars of a galaxy simulations and it looks like this ...
3
votes
0answers
131 views

How does Mathematica identify outliers? [closed]

I don't see anything in the documentation about how Mathematica identifies outliers (in a box plot for example). What definition is being used?
6
votes
0answers
91 views

Behaviour of Plot3D with large numbers [duplicate]

I have a problem with Plot3D. At first I thought it was a problem in general, but while creating a minimal example for posting here, it came out to be a problem with large numbers ...i guess. Let's ...
1
vote
3answers
145 views

Selecting a specific complex number from a list

I have a formula which is producing a large (hundreds of elements) list of complex numbers of the simple form $x+iy$. However I'm only interested in the one value which satisfies the conditions: ...
3
votes
1answer
127 views

fragment loss with ContourPlot3D

I expect to have a chimney-look plot out of the function z = 1/(x^2 + y^2), but what I got is a broken one. Is there a way to get an intact plot from ...
1
vote
4answers
209 views

How to extract only real solutions from the result of Solve

For Example, I have the following polynomial equations: $$ \left\{ \begin{array}{ll} \dfrac{2025 (208 x+5 (y-3446))}{52 (y+90)^2}+\dfrac{300 (8 x-21 y+1920) (y-80)}{7 (x+30)^3}+\frac{300 (80 x-21 ...
4
votes
3answers
177 views

How to get a list of days from July 4th to Oct 4th over a range of years

I'd like to create a list with days from the 4th of July to the 4th of October starting in July 1970 to the current date. I tried to use DateRange, but I'm a bit ...
3
votes
1answer
165 views

How to draw a normalized tangent arrow [closed]

I want to draw a normalized tangent arrow, so I use the Normalize command as follows: ...
2
votes
0answers
74 views

Find where an error occurred in a bunch of command line scripts

I have been using my intuition to solve errors in my Mathematica scripts. But when calculations got more complex and I started getting errors involving code in more participating scripts (a script ...
2
votes
2answers
355 views

What is the proper way to operate on interpolating functions?

I am trying to multiply an interpolating function by -1. If I do this Mathematica does not seem to allow any further operations. Bear with me while I generate the Interpolating Function in question. ...
3
votes
0answers
128 views

Making time-index dependent state-space models - where has the Kalman filter gone?

How does one now implement a discrete set of state space models? I had used KalmanFilter in the old TimeSeries application, but was keen on trying to do all this ...
0
votes
2answers
145 views

Integral with unreliable result

I want to calculate $\int_R^1 \sqrt{r} |\cos((k+\frac{1}{2})\pi r)|dr $ and I get a result from Mathematica. Then I try to check the result putting the value of $k$ and $R$, (k=1 and R=0.5) in the ...
5
votes
1answer
163 views

Deploy a custom function to the cloud

Following my previous topic on how to optimize a complex function, I decided to write a custom algorithm because I need this task to be run locally and on machines with no access to Mathematica. ...
3
votes
1answer
158 views

Is there a function that, given a fraction, will return the general term of its infinite series expansion?

Is here some way to expand a fraction to an infinite sum in mathematica, i.e., a series? I want the general term of the series. For example, $\frac{2}{3(x-1)^3}$
6
votes
3answers
212 views

Problem with WordBoundary in string patterns

I am trying to extract from a string all words that end with "-man", but the problem is that WordBoundary does not seem to work as it returns whole string ignoring ...
0
votes
1answer
206 views

Finding maximum/minimum value of system of inequalites

How would I get the maximum values for x1 and x2 given that I have plotted the region governed by the following system of ...

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