2
votes
2answers
75 views

Local variables whose definitions depend on each other [duplicate]

Consider the following (pseudo-)function definition: f[l_] := Let[{ a = Length[l], b = First[l], c = b/a, }, c*10] So for ...
2
votes
1answer
25 views

ExportString and HTML: where are saved images?

I want to use ExportString to generate HTML expression. Here is an easy example: ExportString[x^3, "HTML", "FullDocument" -> False] gives ...
5
votes
1answer
79 views

ListPolarPlot: 0 Degree at vertical axis

Is it possible to have ListPolarPlot start plotting at the vertical axis? By Default ListPolarPlot gives this result: ...
7
votes
2answers
164 views

Numerical value of physical constants Mathematica 10

Is there a way to use the physical constants in calculations and have Mathematica 10 figure out the final unit and numerical magnitude? When I try ...
1
vote
1answer
47 views
0
votes
0answers
40 views

How to deal with matrices involved in system of SDEs?

This question is in continuation of the the previous posts Solving Stochastic differential equation and Fast Simulations with Compile. What I want to do is numerically solving the epidemic model which ...
3
votes
1answer
46 views

Filling dependence on order of points in ListPlot

ListPlot[{{{1, 0}, {0, 0.5}}, {{1, 1}, {0, 1}}}, Filling -> {1 -> {2}}, FillingStyle -> LightGray, Joined -> True, Frame -> True] Results in no ...
2
votes
0answers
40 views

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

In a fresh Mathematica session evaluating Names["Global`*"] doesn't give an empty list. The result is either {rhs, z} ...
4
votes
1answer
53 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 ...
18
votes
2answers
288 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
88 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 ...
6
votes
1answer
239 views

Tuples without self-loop

I have a simple question coincerning the Mathematica function Tuple. Currently, I apply the following code ...
3
votes
0answers
53 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 ...
0
votes
0answers
52 views

What is the meaning of a result of {{}}? [closed]

What does an output of {{}} mean in Mathematica after solving a system such as: $e^{x}=e^{x}$ for $x$?
2
votes
1answer
116 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
48 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 ...
11
votes
2answers
326 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 ...
6
votes
2answers
105 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. ...
2
votes
0answers
88 views

Power::infy: error using FindFit

I have a 2D data to fit (the Airy type pattern from diffraction of Gaussian beam on the circular aperture). Please see the attached picture. I was going to use a function like ...
3
votes
3answers
94 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
121 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
93 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, ...
0
votes
0answers
11 views

Applying chain rule to evaluate a derivative when the component function is not differentiable at one point [migrated]

I got the following question. Can anyone help me? Thanks! Y is a smooth function of X. and X is a function of r, which kinks at r=r0, but is smooth everywhere else. I was try to compute dY/dX at ...
0
votes
0answers
42 views

Extract the minimum positive root from a quintic [closed]

I need to compute the values of ϵϵ and x2 from the following sytem: ...
0
votes
0answers
77 views

plot $f(x)$ against $\frac{1}{x}$ [closed]

Hi guys this is really a simple question: if i have $f(x)$ how do i plot this function in mathematica against, for example, $\frac{1}{x}$? thanks in advance
12
votes
8answers
509 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: ...
6
votes
2answers
51 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
27 views

Conditions for proper integrals with DSolve on Mathematica

DSolve[{RCS'[s] == SNPH[s] - Sqrt[R2[s] - RCS[s]^2]/b,SNPH'[s] == RCS[s]/a^2, R2'[s] == 2 RCS[s] SNPH[s], RCS[0] == 0., SNPH[0] == snal, R2[0] == ri2}, {RCS, SNPH, R2}, s ]; Here {a,b,snal,r12} are ...
3
votes
5answers
195 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
54 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 ...
2
votes
0answers
45 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
2answers
49 views

Listlineplot starting from 0 [closed]

I got a matrix which looks the following and should be seen as a list of pairs with (x,y) coordinates: test = {{0, 1, 2, 3}, {11000, 23940., 36880., 49820.}}; ...
0
votes
1answer
56 views

NDSolveValue producing message: Input is not an ordinary differential equation

I have an urgent question for my program because I get always an error output for it. I have a partial differential equation that I want to solve with NDSolveValue. ...
0
votes
1answer
40 views
7
votes
5answers
183 views

How to do DateDifference on table items containing dates

I have a Table with data in form {{date}, value}: ...
3
votes
2answers
220 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 ...
6
votes
1answer
143 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. ...
0
votes
0answers
59 views

Why does Mathematica have trouble with this simple set of simultaneous equations? [closed]

The code in question is: Solve[{x == r*Cos[\[Theta]], y == r*Sin[\[Theta]]}, {r, \[Theta]}]. I'm a newbie so this might be fairly basic, but shouldn't this work? ...
-1
votes
0answers
26 views

if f(x) is O(g(n)), then does it follows that h(f(x)) is in O(h(g(x))? [closed]

if f(x) is O(g(n)), then does it follows that h(f(x)) is in O(h(g(x))? Can we prove or disprove it? In my class, we proved that nlogn is in O(log(n!)) But n^n is not in O(n!) It just feels weird.
4
votes
1answer
162 views
6
votes
1answer
155 views

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

Consider this example: ...
0
votes
0answers
87 views

Dual core CPU — Mathematica uses only 29% of one core [closed]

I hope that this question hasn't been answered, yet. At least I couldn't find any answers to that for quite some time now. I am using Mathematica 9 on windows 8. I have two cores. My calculations ...
1
vote
1answer
73 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 ...
5
votes
2answers
288 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
91 views

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

This is relates to a bug was introduced in 10.0.0 and shall be fixed in 10.0.1 It also relates to an issue that has yet to be corrected. After applying GroupBy ...
0
votes
1answer
85 views

Plotting an function defined by an integral [closed]

How can I plot a function defined by an integral. More specific, I have the following equation: $$ T = ...
0
votes
0answers
46 views

Need mathematica to convert images to pure black and white [closed]

So I have a bunch of images (319) that look like this: http://i.imgur.com/a3u8QJi.png I need a script to convert them to pure white and pure black. The only part I need to preserve is very black ...
5
votes
2answers
334 views

Counting the zeros in a factorial expansion [closed]

A number, as big as 1000! (! = factorial) is given. I need to find how many zeros are there in the number. I counted the no of terminal zeros by dividing 5, 25, 125, ... (untill fifth power < ...
4
votes
2answers
57 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
59 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 ...

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