# All Questions

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 ...
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 ...
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: ...
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 ...
47 views

### How to set a variable between 1 and 0, and how to check the FOC is greater or small than 0 by assumption?

I have the following notebook: ...
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 ...
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 ...
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} ...
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 ...
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 ...
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 ...
239 views

### Tuples without self-loop

I have a simple question coincerning the Mathematica function Tuple. Currently, I apply the following code ...
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 ...
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 $x$?
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 ...
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 ...
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 ...
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. ...
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 ...
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 ...
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 ...
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, ...
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 ...
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: ...
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
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: ...
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 ...
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 ...
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 ...
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 ...
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 ...
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.}}; ...
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. ...
40 views

Let ...
183 views

### How to do DateDifference on table items containing dates

I have a Table with data in form {{date}, value}: ...
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 ...
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. ...
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? ...
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.
162 views

### Can I check if an expression is positive using assumptions?

I have the following notebook: ...
155 views

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

Consider this example: ...
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 ...
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 ...
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 ...
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 ...
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 = ...
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 ...
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 < ...