7
votes
2answers
678 views

Symbolic manipulation with unevaluated sums

If I have two expressions with sums in them, like this: $$\begin{align*} b&=\frac{\sum_{i} (x_i - \bar{x})(y_i -\bar{y})}{\sum_{i}(x_i -\bar{x})^2}\\ r&=\frac{\sum_{i} (x_i - \bar{x})(y_i ...
11
votes
2answers
1k views

Trying to fit an unknown extreme distribution

First up, I'm quite new to Mathematica so any hints on better code would be greatly appreciated. I have some histogram frequency data from an unknown distribution that I'm trying to fit. Here's the ...
3
votes
1answer
414 views

Importing file with UCS-2 Little Endian codification

I'm trying to import a text file with UCS-2 Little Endian codification but I can't read it correctly. There's any hidden option to read this files ?? I'd tried with ...
15
votes
3answers
468 views

Grabbing a number of characters around a string pattern

If I have some string data: text = StringTake[ExampleData[{"Text", "DeclarationOfIndependence"}], 400] "When in the Course of human events, it becomes ...
4
votes
1answer
1k views

Solve system of equations related to perspective projection

I'm trying to solve system of equations. I have 4 points before perspective projection and after and I whant to obtain matrix of perspective projection $m_{i,j}$ ($x,y,u,v$ are known , $m_{i,j}$ ...
10
votes
2answers
508 views

Proper way to add vertices to an adjacency matrix

I'm looking for a robust way to add vertices to a graph by modifying its AdjacencyMatrix. Here's what I have so far: ...
19
votes
5answers
966 views

How to perform a depth-first preorder traversal of an expression?

Due to confusion of terminology on my part I asked the wrong question before. Since it has already received other answers I shall not edit it, but instead ask the question I meant to in the first ...
5
votes
3answers
621 views

ContourPlot - plot contour lines for minimum of list of functions == 2nd minimum of list of functions

I have a list of (ten or so) functions of two variables (x and y, say). I would like to plot the boundaries on the x y plane where two functions have the same value - but only the two functions in the ...
15
votes
1answer
393 views

What is Sub Mathematica?

When looking at the locally available licenses, I see four entries: "Mathematica", "MathKernel", "Sub Mathematica" and "Sub Mathkernel". Now "Mathematica", "MathKernel" and "Sub Mathkernel" are clear, ...
2
votes
2answers
556 views

Difference between sub MathKernel and MathKernel

When I try to run Mathematica processes in parallel on a Linux based server, I see that my server allows 7 MathKernels and 28 sub MathKernels. I was wondering what the difference is and how I can take ...
8
votes
2answers
169 views

Behavior of Inner depends on List dimensions?

Consider the following case: ...
10
votes
3answers
568 views

How to select all initialization cells?

Is there an easy way to select all initialization cells (and only those) in a Mathematica notebook?
20
votes
6answers
812 views

How to perform a breadth-first traversal of an expression?

Mathematica provides functions that perform a depth-first traversal, or which use such a traversal, including: Scan, Count, ...
1
vote
1answer
340 views

How to substitute variables in interpolated function?

I'm looking for the way to substitute variables in interpolated function again to original one. (I want to know how to get P(r, theta) from Psol(v, w).) The original variables : ...
5
votes
1answer
232 views

Parts of Module body evaluated in external scope?

I have an expression that suggests that some expressions in a module body are dragging in definitions from outside the scope in a surprising way. First, consider a symbolic constant, ...
7
votes
2answers
216 views

Using mouse back/forward buttons in Mathematica's help system

I have a generic mouse with back/forward buttons. Those buttons are recognized by the system - I can use xev to see that they generate events for buttons number 8 ...
8
votes
4answers
679 views

“Evaluating” polynomials of functions (Symbols)

I want to implement the following type evaluation symbolically $$(f^2g + fg + g)(x) \to f(x)^2 g(x) + f(x) g(x) + g(x)$$ In general, on left hand side there is a polynomial in an arbitrary number of ...
10
votes
2answers
472 views

Simultaneously running the same .m file with different inputs

I have my Mathematica code in a .m file and I run it from the command line with some parameters. I was wondering, if there is no overlap in input and output files, ...
24
votes
4answers
786 views

How can the opacity of a dense data set be automatically chosen?

The problem In a dense data set plotted with opaque points, data points can pile on top of each other. This can cause serious problems with the interpretation of the plots. I'll use as an example a ...
5
votes
1answer
265 views

Build recursion in parallel?

Problem Let's define a simple recursion. f[1] = 1; f[n_] := f[n] = f[n - 1]*n; If I evaluate f in parallel ...
3
votes
1answer
164 views

splitting a list into files

Given is a list with x, y, z coordinates: {{100, 94, -1.112}, {100.05, 94, -1.112}, {100.1, 94, -0.982}, ..., {100, 94.25, -1.112}, {100.05, 94.25, -0.855}, {100.1, 94.25, -0.728}, ..., ...
11
votes
3answers
5k views

Custom contour labels in ContourPlot

Suppose I wanted to draw the zero contour for the function $$d^2-g.$$ I could use the following code: ...
1
vote
1answer
3k views

solve non-linear system of equations

I have a system of equations and I want to solve it to get x, y $$\begin{cases} u= C_{1}+(x-C_{1})(1+k_{1}((x-C_{1})(x-C_{1})+(y-C_{2})(y-C_{2}))) \\ \\ v= ...
4
votes
1answer
476 views

Multiple simultaneous events in EventLocator method for NDSolve

I'm using NDSolve to integrate a system of ODEs, and EventLocator to stop the integration when it leaves a certain region in phase space. This works perfectly as it should. However, I've also added ...
35
votes
4answers
2k views

Remove image background of headshot in Mathematica?

For example, using ExampleData[{"TestImage", "Girl2"}]: what's a general way to make the background transparent? I've tried various combinations of ...
3
votes
2answers
371 views

Dynamic lists as function arguments

Suppose I have a function that requires a list is as input. I.e. f[list_]:=DoSomethingWithList Now, if I pass a variable as Dynamic like this ...
3
votes
2answers
156 views

How to change type order in PearsonDistribution?

I need to estimate a Pearson distribution from a batch of tables tab: ...
7
votes
2answers
1k views

Controlling the 2D $x–y$ aspect ratio of a 3D plot

I have some data representing a nested list, each element being composed of 3 real numbers like ...
6
votes
3answers
737 views

Adapt ColorFunction in Array Plot

The problem I'm facing is how to adapt ColorFunction so that it ranges from green (low values) to red (high values): ...
6
votes
2answers
847 views

3- dimensional plot of 2-dimensional systems of differential equations

Let's take this first example of a 2D output: ...
12
votes
1answer
1k views

AccuracyGoal, PrecisionGoal, WorkingPrecision and NDSolve

I'm trying to understand exactly what WorkingPrecision, AccuracyGoal and PrecisionGoal mean ...
9
votes
1answer
532 views

Can you call a C function that takes function pointers as arguments?

I want to use MathLink to call a function I wrote in C. However, similar to an integrator, it takes a function pointer as an argument and applies it on numbers depending on the other arguments. I ...
11
votes
1answer
620 views

Visualize cluster distances in DendrogramPlot

I want to perform a cluster analysis using the HierarchicalClustering package. Is there a way to display the inter-cluster distances in a dendrogram plot? An ...
3
votes
2answers
176 views

Why didn't Reduce give me the right result?

My code: Clear[r1, r2]; par[r1_, r2_] := r1 r2 / (r1 + r2); Reduce[{5 par[r2, 32000]/(r1 + par[r2, 32000]) == 1.8 && par[r1, r2] == 5000}, {r1, r2}] ...
6
votes
2answers
203 views

Can individual locators in LocatorPane be temporarily disabled?

This follows up on another question about the sensitivity of Locators in a a LocatorPane. I would like to be able to enable/disable individual locators in a LocatorPane. In the simplified version of ...
2
votes
1answer
1k views

Solve matrix equation A*X=X*B using LeastSquares

I want to solve matrix equation A*X=X*B using LeastSquares method, but it is suited for equation like A*X=B. All matrices are 3x3 ...
1
vote
2answers
2k views

Find the dimensions of a cylindrical can that will minimize the cost of the material

A cylindrical can is to be made to hold 1 L of oil. Find the dimensions that will minimize the cost of the metal to manufacture the can. This is a standard calculus problem. The volume of the ...
4
votes
2answers
137 views

Thread[] seems to reset changes made with Manipulate[]

Recently I have been working on group theory and I have found checking for associativity for specific Cayley tables to be rather tedious so I wrote a program to do it for me. Most of the time I would ...
15
votes
1answer
307 views

Polynomial expectations of generic distributions

Summary Polynomial expectations depend only moments and cross moments of a multivariate distribution. I would like to use Expectation to compute polynomial ...
11
votes
2answers
396 views

Word Squares and Beyond

A word square is a set of words which, when placed in a grid, read the same horizontally and vertically. For example, the following is an English word square of order 5: ...
2
votes
2answers
1k views

Animation of Differential Equations from NDSolve with ParametricPlot3D and Evaluate

I have a system of differential equations (referred to as "s") and use NDSolve to obtain the solution. I substitute the interpolated functions for the original ...
3
votes
1answer
239 views

Efficiently importing XPM matrix data into Mathematica

The XPM file format is an image file format. Although it is primarily intended for icon pixmaps, it can also be used to store matrix data. For example, the GROMACS chemical simulation package uses ...
5
votes
2answers
160 views

How to get the boolean value of an inequality involving an InterpolatingFunction?

Here's the code: yan = FunctionInterpolation[x^2, {x, -1, 1}]; FullSimplify[yan[x] > -1, -1 < x < 1] Needless to say, what I expect to see in the output ...
14
votes
5answers
2k views

How to use filling in ContourPlot

I want to fill region between different contours, e.g. ContourPlot[{c1 = f1, c2 = f2}, ...] a la the filling options for Plot ...
1
vote
1answer
195 views

Trying to generate a function from InterpolatingFunction with FunctionInterpolation

Here is the code (I'm sorry to give you such a complex code sample but I failed to reproduce the error with a simpler InterpolatingFunction): ...
6
votes
3answers
588 views

What function can I use to evaluate $(x+y)^2$ to $x^2 + 2xy + y^2$?

What function can I use to evaluate $(x+y)^2$ to $x^2 + 2xy + y^2$? I want to evaluate It and I've tried to use the most obvious way: simply typing and evaluating $(x+y)^2$, But it gives me only ...
2
votes
1answer
391 views

Substituting Symbol font for Mathematica's custom font in exported plots and other graphics

Mathematica includes some custom fonts that allow you to use a wide range of mathematical symbols in output. For example, one can write: ...
6
votes
2answers
407 views

How do I transform a rasterized graphic's coordinates back to its original ListPlot data coordinates?

From this question I successfully made an elliptical fit for my data. However, when I try and collect the datapoints within the ellipse via this question the coordinates of my ellipse correspond to an ...
1
vote
1answer
262 views

Code to draw geometry doesn't run

I'm new to Mathematica and have no background whatsoever in programming, although I will teach myself soon. I was wondering if one of you programming pros could help me out. I received a code from ...
-1
votes
1answer
402 views

simplifying equations [closed]

I have a question that seems easy but I can't solve it. I have an equation like: eqgama = -8.33208*10^56 g1 + 8.18264*10^56 g1^2 == -1.42093*10^56 I use the ...

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