2
votes
0answers
79 views

Some global variables are defined even at the start of a fresh session [duplicate]

In a fresh Mathematica session evaluating Names["Global`*"] doesn't give an empty list. The result is either {rhs, z} ...
5
votes
1answer
120 views

Problem with general assumptions

I hope I am not to redundant with my questions. As part of solving a physical problem, I want to assume once and for all that all my variables and parameters are real, positive and finite. Is it ...
20
votes
2answers
585 views

Object separation from a 2.5D surface

I'm trying to identify the shape and the boundaries of objects. The data was generated with a laser scanner and represent the surface of an area in which many boulders lay on the ground and making up ...
0
votes
1answer
151 views

Specifying initial conditions for a PDE

I have simple diffusion equation with point source at c(0, t) = 1 and initial condition c(elsewhere, 0) = 0. How should I apply ...
7
votes
1answer
319 views

Tuples without self-loop

I have a simple question coincerning the Mathematica function Tuple. Currently, I apply the following code ...
3
votes
0answers
91 views

Efficient processing of Special Ordered Sets with LinearProgramming

I'm playing with integer linear programming, especially problems involving lots of constraints which would appear to be special ordered sets. Below is a toy example, three last rows of the matrix ...
2
votes
1answer
216 views

How to solve three equations with four unknowns iteratively?

I have three equations of the form $\quad \eta = f(N1L, N2L)$ $\quad N1L = g(\eta, R)$ $\quad N2L = h(\eta, R)$ I want to eliminate $\eta$, so that I can get $N1L$ and $N2L$ for a range of $R$. I ...
2
votes
0answers
57 views

Program file deleted while running

I have a program running for some time at one computer. Today, unintentionally, I edited the program file from another computer (I use Dropbox), and the program kept running. Trying to correct my ...
15
votes
2answers
2k views

Find maximum value of interpolation function - obviously wrong result

Minimizing and maximizing interpolation function has already been asked and answered, see here for example. Yet, I observe a strange behaviour. Well, I can understand that the wrong guess of ...
9
votes
3answers
423 views

Export MatrixPlot graphics to PDF

I am trying to export a plot generated by MatrixPlot to PDF but am having problems with the way the exported PDF is rendered. ...
3
votes
3answers
171 views

Solving determinant of a Kronecker product of matrices gives a numerical error - why?

I am doing the following steps (code at the end of the post): I start with a 2x2 matrix (smatrix), which is a function of a single variable (u2). I want to set the determinant of this matrix ...
3
votes
3answers
461 views

Transformation of Derivatives under change of coordinates [duplicate]

I have an expression depending on the two variables z and t, and the derivative of a known function $f(t,z)$. Something like: $$myexp \ =\ t\ z\ \partial_z\ f(t,z)$$ Now I want to make a change of ...
1
vote
2answers
151 views

How to do a region plot with many functions [duplicate]

Hello i am trying to compare many function, i want to see witch one as the lowest value depending on 2 variables. My solution so far is something like this: I have 7 function: P1 P2 P3 P4 P5 P6 P7, ...
16
votes
8answers
710 views

UnFlatten an array into a ragged matrix

Trying to unflatten an array that was part of ragged array of sub matrices. As input we have flattened array: ...
7
votes
2answers
143 views

Recursive function with array of variables

I am trying to create a recursive function which works with an increasing array of variables. Since the formula is quite complex, i will try to simplify my example to the core of my problem. The ...
1
vote
0answers
63 views
4
votes
5answers
768 views

Ordering the Boundary points of a Polygon

I feel like this should be simple, but I keep running into walls. Say someone gives you the coordinates of the vertices of a pentagon and the center point of the hexagon. Is there any way to get an ...
0
votes
1answer
324 views

Interpolation of 4D data

To create a table and an interpolation function of 3D data T=f(X,Y) I have the answer here: interpolation of 3D data How to create a table/interpolation function of 4D data T=f(X,Y,R)? If I do ...
8
votes
0answers
517 views

Problems running Mathematica 10 with Workbench 2 Windows 7 64 bit

My Workbench runs perfectly using Mathematica 9, however simple things which run just using the Mathematica 10 front end won't run when using Mathematica 10 and Workbench 2. These simple two lines of ...
1
vote
1answer
48 views
8
votes
5answers
229 views

How to do DateDifference on table items containing dates

I have a Table with data in form {{date}, value}: ...
3
votes
2answers
399 views

How to create a 'shortest-path link matrix'?

I am currently struggling with a problem in Mathematica. I have a randomly generated weighted Barabasi-Albert graph and a corresponding demand matrix of the same size. I'm generating the graph with ...
7
votes
1answer
166 views

Wrong values at the boundary of differential equation solution

I have a second order ordinary differential equation and want to solve it numerically. Although I have specified values at the boundary, Mathematica solution does not match with boundary conditions. ...
4
votes
1answer
418 views

Can I check if an expression is positive using assumptions?

I have the following notebook: ...
6
votes
1answer
194 views

How to make Epilog render behind the main plot [duplicate]

Consider this example: ...
1
vote
1answer
156 views

Missing arrow tips and colors

My main problem is: I plotted a curve here, but the tip of some arrows are missing. Why does this happen, and how can I fix this? Not the main problem: Also, I once tried to make the arrows with ...
6
votes
2answers
390 views

Is it possible to produce “tilt-shift” effect in Mathematica?

I attempted to produce a kind of miniature faking look from a street scene photo. I tried to shift the perspective lines close to parallel to each other to obtain such effect. However, the result ...
5
votes
2answers
203 views

How to lookup by a string key after GroupBy? Inconsistent data type handling

This is relates to a bug that was introduced in 10.0.0 and fixed in 10.0.1 It also relates to an issue that has yet to be corrected. After applying GroupBy to ...
4
votes
2answers
85 views

Rational display with Quantity

Why is that Power[Quantity["ElectricConstant"],-1] is represent different of Power[Pi,-1] What I am doing wrong ?
0
votes
1answer
105 views

Unusual Slow Down with LocatorPane/DynamicModule

I have coded up a little interactive DynamicModule to help me with image processing/segmentation of stacks of timelapse microscopy images. I am experiencing a crippling slow down in the ...
4
votes
1answer
384 views

Fredholm integral equation of the second kind with kernel containing Bessel and Struve functions

I need to solve this Fredholm integral equation of the second kind: f[s]+integrate[f[t] K[s,t],{t,0,1}]=s where ...
1
vote
0answers
145 views

Compiler stack overflow [closed]

I tried to compile a huge function. I used these options: ...
7
votes
2answers
201 views

Replace Missing[Unmatched] with zero

After a left JoinAcross, I have a number of Missing["Unmatched"] values in my list of associations. I'd like to set them all ...
5
votes
1answer
132 views

Grid rows height & SpanFromAbove issue

I would like to understand why the following code produces such a different result (Mathematica 9, Win7). Is this a bug? Is there a way to avoid this line height problem? ...
10
votes
5answers
580 views

What is my problem with MeshFunction?

I want plot the max value in a sine plot. We can use the following code ...
6
votes
1answer
286 views

Citation of the algorithms used in FindGraphCommunities

For my research work I need to put a comparison of different community detection algorithms. Instead of implementing all those algorithms once again, I would like to use the methods already provided ...
2
votes
0answers
93 views

An efficient way to merge a pair of 4d arrays of non regular length lists

Question I have two 4 dimensional non regular length lists of complex values. I have working code however it seems quite slow and I am not sure how I could improve this. Mathematically I am trying ...
12
votes
1answer
858 views

Blurred frontend text in Mathematica 10, Windows, High-DPI Display

So I have recently upgraded to a Windows ultrabook with a high resolution display. All my software seems to cope just fine with the high resolution, except for Mathematica 10. Mathematica seems to ...
3
votes
2answers
309 views

Selectively updating individual graphics in a dynamic, multiple-plot Show

Suppose Show contains multiple graphics objects that differ markedly in the amount of computation needed for their display. Hence, when dynamically updating only ...
4
votes
0answers
52 views

Is it possible to pass a “shared” integer in librarylink?

MTensor supports shared pass, where the argument can be modified in the library function and that modification can be seen in Mathematica side. Is it possible to do the same thing to a integer or ...
1
vote
1answer
151 views

Locators, lists of variable length, all in Manipulate

I'm trying to implement a complicated Manipulate[] interface. I'm not really interested in working code, but for those interested, I would like the program to allow you to drag around a variable ...
6
votes
0answers
80 views

Listable compiled functions used in NMinimize [duplicate]

This is an example from MMA: cListable = Compile[{x}, (x-1)^2, RuntimeAttributes -> {Listable}] In case of single entry: ...
7
votes
1answer
366 views

Exporting a compiled function for later use

I wish to export compiled functions for later use. This means that I do not want the compiled function to be recompiled every time I reload it. It also means that if my compiled function was for ...
5
votes
3answers
262 views

difficulty abstracting the OptionValue pattern

I am building lots of functions that use Options and OptionValue and wanted to reduce the redundancy in the expressions that ...
7
votes
5answers
527 views

Find patterns in a list

again, I have a list like this: ...
4
votes
1answer
135 views

Bad numerical approximations

I'm trying to do some calculations here, but for some reason Mathematica starts using numerical approximations that are no good for my work. Specifically: ...
11
votes
0answers
123 views

Proper EdgeForm setting so boundary appears entirely within shape

I have two neighboring (complicated) polygons that I want to be displayed with thick boundaries, however the two shapes border one another, and as EdgeForm places the line centered upon the polygon's ...
3
votes
1answer
184 views

FindFit with parameters which are simultaneously in initial conditions

I have RLC circuit. I would like to find R and L by using FindFit, but L is in initial condition and I have problem with it. Could you help me ? ...
1
vote
1answer
127 views

How to factorise a variable out of an indefinite sum?

(I should start by saying I'm a total beginner with Mathematica, so if the answer needs code I'll need it spelled out quite clearly, the learning curve for this is proving steep!) Basically what I am ...
5
votes
3answers
560 views

Creating Correlation Table (and Working) With Missing Data

I am working with data that contains missing values (I have several variables (across the columns) and several observations (across the rows) in an excel spreadsheet). Example of the data structure: ...

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