0
votes
1answer
417 views

Trying to solve a transcendental equation involving Bessel functions

I've never used Mathematica before and am trying to numerically solve equation (12) from this paper. Ideally I'd be able to find the smallest value of $x_{n\nu}$ for $\exp(-kr\pi)$ close to 1, and ...
19
votes
2answers
733 views

How to make a curve selectable from a scaned image and convert it to a list of coordinates

I have a scanned image (binary-ized): Is there any way to reduce one of these curved lines (full or dotted) to a series of its coordinates (e.g., sampling interval of 0.01 on x-axis)? I've read ...
2
votes
2answers
187 views

Set PointSize to pixel size

I have a set of 1million 2D points and I would like to produce an image 200x200 pixels where each point will have the size of a pixel (no more). Additionally each point may repeats several times so I ...
4
votes
1answer
163 views

What are the hidden specifications for FindRoot

The Help page of FindRoot says: "by default, FindRoot uses Newton's method (Newton-Raphson) to solve a nonlinear system" (or a nonlinear equation I ...
3
votes
3answers
297 views

Data Table Manipulation

Suppose that I have the following ...
2
votes
1answer
91 views

SQL Queries with the Table function

Given the following connection to an SQL query works but the data comes out wrong: ...
3
votes
3answers
200 views

FindRoot constrained to maximum

I am using FindRoot to find the local maximum op some function, by examining where its derivative is zero. However, keeping the starting value the same, sometimes ...
2
votes
1answer
111 views

Accessing Draw Tools objects with notebook commands

In a notebook I would like to be able to access and modify the properties of draw tools objects after I've drawn them on a graph by hand. For example, if make a plot and, with draw tools, make a ...
0
votes
0answers
16 views

?AspectRatio? setting to obtain equal length pr pixel on all axes [duplicate]

Like these does: Show[Graphics[Rectangle[{2, 1}, {15, 2}]]] ParametricPlot[{t,t t},{t,0,2}] how do I create a Plot[] with ...
1
vote
0answers
74 views

Mathematica exit when calling plot. Bug?

I'm currently studing the behaviour of some integral for which I cant find an analytic solution. As this function depend on a vector on the unit sphere, I first defined it with 3 parameters before ...
1
vote
1answer
366 views

Why does Mathematice dislike my boundary condition in NDSolve?

im trying to solve a PDE-System, with the "periodic boundary condition" c[t,0]==4*c[t,2pi] But mathenmatica says: NDSolve::bcedge: "Boundary condition ...
7
votes
3answers
452 views

Mathematica style (drawing cubes)

I wanted to draw (lattice-aligned) unit cubes inside a sphere with a given radius centered on the origin, so I wrote this program: ...
2
votes
2answers
575 views

Solving simultaneous exponential equations

In[1]: Solve[{(1 + k)^n == 0.6, (1 + k)^(n + 1) == 0.3}, {n, k}] Solve::ifun: Inverse functions are being used by Solve, so some solutions may not be found; ...
4
votes
2answers
473 views

How to transform transfer functions into differential equations?

is there a way with Mathematica to transform transferfunctions (Laplace) into differential equations? Let's say I have the transfer function $\frac{Y(s)}{U(s)}=\text{Kp} \left(\frac{1}{s ...
0
votes
0answers
34 views

Using Map with functions that take a parameter [duplicate]

I have a list l={{0, 0, 0, 3}, {0, 0, 0, 3}, {0, 0, 1, 2}} And I would like to obtain the number of zeros in each sublist: ...
2
votes
2answers
544 views

Removing trailing zeros from a list

If I have a list like list1={2334.,342.,0.,0.,2322.,0.,0.,0.,0.,,,,,,}; it's easy to remove to trailing blanks with ...
1
vote
1answer
233 views

Numerical Instability?

Current Status Please skip ahead to Update 2: the key questions are now: 1/ Why does Mma generally fail to find the minimum for a well behaved function when the function does not have infinite ...
3
votes
0answers
107 views

Deciding whether a semi-algebraic set is empty. Which command is best?

[Update] I was able to prove that the "larger" set $ 1\ge x \ge y,w \ge 0$ and $p(x,y,w)>0 $ is empty with another computer algebra system in my slow laptop in few minutes but in Mathematica even ...
1
vote
2answers
77 views

CDF of TransformedDistribution Not Returned And No Error Message Produced

I am unable to get Mathematica to return the CDF of a distribution produced by TransformedDistribution. It "executes" for 6 hours on my machine and then returns a blank plot. Could someone execute the ...
-1
votes
1answer
75 views

How to fit one parametric array to another numerical array?

I have two arrays of length n. One of them is obtained by experiment, so every element of the array is a number. The other array is parametric, each element is a ...
1
vote
1answer
74 views

ReadList error with negative very small numbers

When I try to import data with ReadList from a file containing very small numbers (~10^-318), positive data is handled well, ...
0
votes
1answer
112 views

Writing equations from Mathematica in Matlab [duplicate]

I would like to use mathematical equations directly in Matlab. I found one thread describing about a built in Matlab file i.e. ToMatlab.m. I am able to download this file, however, I could n't able to ...
0
votes
1answer
54 views

Replacing whole strings

I imported a text and seperated al words by using StringCases. After this I would like to manipulate the text, for example to replace all singular verbs to plural. ...
4
votes
2answers
131 views

Values (or positions) of array row elements within a specified number of positions from target value

I have the need to collect values from the rows of rectangular arrays of arbitrary precision integers, given a target element value and allowed "distance" (positions +/- within the row from found ...
4
votes
1answer
85 views

OpenCLLink eating up all host memory

I am calling lots of OpenCL functions from Mathematica. The problem is that the memory the kernel uses grows and grows until the RAM is fully occupied. I have created a small piece of code to ...
2
votes
0answers
81 views

Front End - Bug in Edit->Find?

As a beginner I make notes in my notebooks on what I am learning as I go along, and I have also referenced the help files by pasting hyperlinks from them - this seems to break the Find function. Is ...
0
votes
1answer
440 views

Plot 3D density

I have data that is in four columns. The x y and z are just the coordinates and the fourth is my data. This is not a function. This is electron density in a copper cell and I'm trying to display it ...
2
votes
1answer
85 views

Why can I edit only one character of the output of a Dynamic expression?

Try this: DynamicModule[{foo = \[Placeholder]}, foo] Note how we're able to edit the placeholder in the output, e.g. replace it with 42: ...
1
vote
1answer
151 views

How to get the dimensions of a rectangle?

Suppose I create a Rectangle of dimensions 1 and 3. Is there any function in Mathematica that I can use to recover the dimensions of the original rectangle? If there is no such a function, is there a ...
3
votes
4answers
561 views

More elegant way

I read ReplaceOrRemoveInvalidOrMissingData Mathematica documentation, and I tried to apply the same approach to my dataset. I've got two problems, but one is only a style problem! There is one more ...
2
votes
2answers
268 views

Change Meta-Information “Title” of PDF file in Export

Whenever I export a PDF file in Mathematica with the Export command, the meta-info of the pdf file will have the title as "Temporary Clipboard 0". I want to change the title. But using: ...
5
votes
1answer
567 views

Asymptotic expansion

I wanted to expand a function of $x$ about $x=\infty$ and see its coefficients as a function of the parameters $m,n,q,y$ and I wrote this - but it didn't work! It gave me back a very complicated ...
4
votes
3answers
234 views

Increasing the precision of a calculation

Clearly I have misunderstood how to do this: I seem unable to understand how to get more digits out of a calculation and I can't see why - the following piece of code illustrates the issue. ...
3
votes
1answer
274 views

project moving point onto a line

The following code displays three solutions to the logistic ODE with an animated points that follow the solutions.. My goal is to project the solutions on to a vertical phase line. I need to be able ...
2
votes
1answer
118 views

how to distinguish clockwise from counterclockwise rotation

I need to distiguish the true rotation of a vector (time dependent, solution of a system of two coupled differential equation) respect a fixed vector. As showed in the follow,neither ...
0
votes
1answer
185 views

Visualize fixed points and stable points in 4D

I have a list of 4 dimensional data points which are sum to one and always positive. These points are the fixed points of the 4 dimensional nonlinear ODE. I also found the stable points of the system ...
0
votes
2answers
118 views

Distributing value of variable to specific kernel

I want to distribute the value of a variable to a specific kernel in a parallel computing setup. Using DistributeDefinitions of course does the job, but it ...
6
votes
2answers
502 views

Correct fourier scaling and high-resolution frequency identification

I have a dataset of amplitude versus time $(t,A(t))$ and I need to extract the dominant frequency and amplitude, and also get the amplitude at one other specific frequency. My data looks like this: ...
3
votes
1answer
521 views

ReadList with header and foot lines

I want to do some large data analysis, and i want to be able to import files in a fast way. I tried Import, but it is quite slow; ReadList takes half the time. This is the code I was using: ...
9
votes
1answer
435 views

Compile function which calls other functions to C

I have a function which calls other functions and I would like to compile it to C code. For example: ...
5
votes
1answer
417 views

Mathematica-To-MATLAB Dictionary!

Is there a dictionary to translate Mathematica functions and commands to MATLAB?
0
votes
3answers
100 views

Function to naming columns

I often import files from excel or csv files and they come in a format like this: ...
4
votes
2answers
277 views

DynamicModule/Dynamic CheckboxBar Slow for Large Lists

I am trying to create a dynamic construct that takes a large list of expressions and allows the user to interactively select any number of entries for further manipulation. This is what I have ...
5
votes
2answers
181 views

How to get the series expansion of $e^{x^a}$ at $x=0$?

I want to have a series expansion of $e^{x^a}$ or $e^{c_1x^a+c_2x^b}$ at $x=0$, but Series cannot give any useful result even if the assumption $a>0$ is ...
0
votes
0answers
98 views

How to modify the file “KeyEventTranslations.tr” to use Enter to evaluate the current cell? [duplicate]

I asked the following question before, but I do not think it has been fully answered. By default, we use Shift+Enter to evaluate the current cell, and use Enter to get a new line. Is there a way ...
4
votes
0answers
92 views

Converting problem into form involving Probability

I want to solve the following problem symbolically, using Probability: What is the probability of the first random variate of a set to be present more than ...
2
votes
1answer
111 views

RSolve: Errors while solving Partial Difference Equation

I tried solving following partial difference equation in Mathematica by typing ...
2
votes
2answers
602 views

Convert list to sequence

I was just thinking how Tuples was created so , I came up with this, ...
3
votes
3answers
169 views

Performance on Multinomial Deviate is slow

Most of the time in my program is spent on this single line of code: out = RandomVariate[MultinomialDistribution[nt, tmp]]; ...
11
votes
3answers
212 views

Head of a MatrixForm expression?

An example in http://www-zeuthen.desy.de/theory/capp2005/Course/hahn/mathematica.pdf amounts to the following ...

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