4
votes
1answer
3k views

NonlinearModelFit does not find a good fit

I am trying to fit my data to the following function, $$\frac{a b t \left(\log \left(\frac{-a d t+a t-1}{a d t}\right)-2\right)}{4 (a t-1)}-c$$ ...
1
vote
0answers
144 views

Increase optimization processing speed

As you know, sometimes numerically solving of optimization problems takes several minutes. For this reason 2 question came up to me: 1 - When one is abort the optimization procedure, how it is ...
4
votes
1answer
97 views

Control Object Annoyance

This may seem like is a trivial annoyance, but it really is a control object "convenience of use" issue. Example: I want to use a popup menu to determine which Excel worksheet I take data from, as ...
1
vote
1answer
1k views

How can you convert a matrix back into a list of lists?

It is very simple in Mathematica to convert a list of lists into a matrix: all you need to do is apply the //MatrixForm function to it and voila. Is it possible ...
7
votes
1answer
174 views

How to inherit options by scoping?

Consider the following example: you have a function framed producing a cell with a button that, when pushed, calls framed again. ...
3
votes
1answer
252 views

How to fill a whole rectangle with text?

I have a rectangle with specified dimensions and I'd like to fill it with text, so that the text uses all (well, as much as possible) of the available area. I tried to do it with ...
2
votes
3answers
381 views

Re-arranging / selecting of a data table very slow in For loop [duplicate]

My task is quite simple; I have a table of data like M = {{1,2}, {1,3}, {3,4}, {5,1}, {6,9}, {6,8}, {6,1}}; so the table is sorted with respect to the first ...
3
votes
1answer
334 views

NDSolve with varying PrecisionGoal and WorkingPrecision

Sometimes we need higher numerical precision to deal with large number cancellation in an equation. But if this cancellation happens only in a small (and known) parameter space, would it be possible ...
4
votes
2answers
288 views

Floating point addition not associative

Can anybody explain the following behavior? x = 0.2 + (0.3 + 0.1); y = (0.2 + 0.3) + 0.1; x == y (* -> True *) But actually the variables do not exactly ...
1
vote
0answers
71 views

Dot shading a.k.a. Stippling effect [duplicate]

I am trying to convert grayscale images to black and white, where I hope to have certain artistic effect, called stippling: I have tried two methods; dithering (with ...
1
vote
1answer
335 views

How to export data in scientific form

I am having an issue about how to export data in its scientific form using Mathematica. To be concrete, I define a list ...
4
votes
1answer
757 views

Testing for OLS Heteroscedasticity White's General Test

I've done my best to search the help and google White's test (http://en.wikipedia.org/wiki/White_test) in Mathematica. Can anyone point me to a function or Mathematica reference for this or do you ...
0
votes
0answers
36 views

Check if a (possibly nested) list is real [duplicate]

I have a very large matrix of numbers. I want to check if all its entries are real. At the moment I am using realQ = And @@ Thread[Flatten[Im @ #] == 0] & Is ...
9
votes
5answers
751 views

Take both of the diagonals through an element in a matrix

I have a matrix like this: Reverse@Array[List, {8, 8}] // MatrixForm I need a function that given an element of this matrix will return all the elements ...
6
votes
2answers
481 views

Flow/graph-based programming in Mathematica?

Is it possible in Mathematica to write a program inside a graph? For example if you have a bunch of different If[] statements that you need to embed within one ...
0
votes
0answers
244 views

How to run Mathematica kernel on remote server?

This might be a really stupid question, but I have no idea how to get my copy of Mathematica to run on a remote server in the cloud. I have a Webfaction account and a copy of Mathematica installed ...
0
votes
2answers
382 views

Problems with Manipulating a piecewise function

I'm having problems with changing some parameters with "manipulate" in a piecewise function. The code i'm working with is: ...
46
votes
2answers
2k views

How can I add drop shadows and specular highlights to 2D graphics?

I thought I'd share some code in the form of a self-answered question, but other answers are of course welcome. Drop shadows are a familiar visual effect, giving the impression of a graphical element ...
1
vote
1answer
340 views

GUI and Dynamic update problems

I have made many functions that connect to a MySQL database perform operations then export exel spreadsheet. I also import spreadsheet data into the database. I would like to get many of these ...
3
votes
2answers
183 views

Stopping a head from evaluating more than once

While attempting to answer my own question, Is there a way to "hold" prefix / infix / postfix notation?, I came across the need to evaluate a recursive function only one level deep. For ...
3
votes
1answer
144 views

How to transform an equation so that the coefficient of a certain term becomes 1

Say I have an equation like A + 5 B + 10 C == 0 and I want to have Mathematica write this as (A/5) + B + 2 C == 0 i.e., I ...
1
vote
1answer
258 views

Splitting dates into groups in half year steps

list = DayRange[{1999, 1, 1}, {2014, 2, 6}] I want to split this list into sublists one and a half year long, moving a half year forward every time. That would ...
3
votes
1answer
233 views

Writing results directly to file

I am trying to find all simple paths in a large directed graph (542 vertex, density ~ 5%) between two nodes. For this purpose, I use the algorithm from this thread. Unfortunately, my computer is ...
1
vote
2answers
224 views

Is there a way to “hold” prefix / infix / postfix notation?

Is it possible to preserve a specific style of notation in $Mathematica$ output? foo // bar (* bar[foo] *) Hold[foo // bar] (* bar[foo] *) I'm writing some code ...
1
vote
1answer
107 views

How to get all permutation of k-partition

If I want to get the list of k-partition, and the rule are below: here are k partitions all elements of partition are in the range of 1 to 30. the total of ...
8
votes
2answers
480 views

Young Tableaux Miscellanea

I have a problem which is mostly neatly described by using Young Tableaux. Mathematica seems to have these Tableaux built in, except that the Tableaux function is ...
8
votes
2answers
962 views

StreamPlot for Bifurcation Diagram

When we do a StreamPlot, I want to show the bifurcation when $a = 0$ transitions to $a >0$, but do not see a better way to do this than the following. ...
0
votes
3answers
174 views

Implementing nested subtotals

Inserting a nested subtotal in a spreadsheet is a facility that Excel performs very well. But if a subset of this facility can be implemented in MMA for a table which needs it the hassle of its ...
2
votes
1answer
296 views

Extract coefficients of differential form in package RGTC

I am using the Package RGTC to do some calculations in Supergravity. It allows to define differential forms after specifying a co-frame. I am working in with the 10d coordinates $\{t,x,y,z,r,\phi_1,\...
6
votes
1answer
120 views

Why does a heavy background slow LocatorPane from updating, even if only the locators are Dynamic?

I'm having some trouble getting a dynamic plot to operate efficiently, and I think I've tracked down at least part of the problem to some pretty weird behaviour on the part of ...
1
vote
1answer
542 views

Import invocation fails with Get::noopen : Cannot open JLink error

The following function call fails when I invoke it in a fresh Mathematica session: ...
1
vote
2answers
275 views

MathLink Graphical Output (Plots) to File

In a custom Mathematica frontend based on MathLink I try to make use of plots produced in Notebooks. The idea is to write them to files whenever they get produced. According to C-code snippets I ...
0
votes
1answer
97 views

Using Derivative with list in curly brackets

I'd like to make a formula for a sum containing Derivative where the number of arguments in the latter depends on an input parameter n. Also involved is a list <...
13
votes
2answers
162 views

Why the Block command does not forget the $ContextPath variable

I do not understand this behavior: ...
3
votes
2answers
641 views

Copy and paste behaviour with Subscript

I tend to use a lot of subscripts in my code, and I am aware that copy and paste of subscripts from Mathematica to MathematicaSE (or any text editor, for that matter) is screwy in the sense that $a_b$ ...
1
vote
1answer
187 views

How to define an n-variate empirical distribution function probability for any n?

I'm using Mathematica 9.0 to calculate the probability according to the empirical distribution function (EDF) of some sample data. Afterwords this is included in a maximization stage so I define this ...
0
votes
1answer
165 views

Why do InputFields not respond in Manipulate utilizing FindGeometricTransform?

In the following code changing the InputField does not result in observing changes in a result from FindGeometricTransform, but ...
18
votes
2answers
329 views

Third argument of Compile

In his last comment on this answer, halirutan shows an example in which the third argument of Compile does not have any effect. The example is as follows. ...
1
vote
1answer
181 views

How to assign Subscript[C, i] to a Sum?

What I want to show is: Plot3D[ Sum[1000*Subscript[C, i]^2/(1000*Subscript[C, i] - 600)^r, {i, 1, k}], {k, 1, 30}, {r, 0.1, 1.5}] And, I want the list of <...
2
votes
1answer
287 views

Find missing values in time series and fill them with Na

I have this list list = {{1, 3}, {3, 7}}; representing a time series from t = 1 to t = 4. How would I go about filling the missing values so that my list looks ...
4
votes
1answer
2k views

Why is Solve returning an empty list?

I evaluate ...
9
votes
2answers
324 views

How to see which arguments are passed into a function

It is often that one wonders which arguments are evaluated before being passed into a function. I would like to know if it is possible to see which argumets are being passed into a function without ...
1
vote
2answers
106 views

Apply a function to each element of a list and sum it

I have a list {-1.8, 1.44, 0.2736, -1.72514, 1.17612} where each element stands for a value of x. e.g. $x1 = -1.8$, $x2 = 1.44$ and so on. How can I find the ...
4
votes
0answers
212 views

Non-linear integral equation [closed]

I'm trying to solve with Mathematica an integral equation. I found this excellent answer (How to solve a non-linear integral equation?) solving with a collocation method a problem which can be ...
1
vote
1answer
39 views

How to assign a list of subsript?

I want to assign Subscript[C,i] by mapping a specific list. For example, the list is {1,2,3,4}, and I want to assign 1 to C1, 2 to C2, 3 to C3 and 4 to C4. How should I do? Many thanks:)
26
votes
1answer
467 views

Are greek symbols causing different evaluation?

I've updated today to Mathematica 9.0.1.0 from version 8 and found something that absolutely confuses me. Let us define a piecewise function: ...
1
vote
1answer
108 views

Getting error FullSimplify::infd: … simplified to ComplexInfinity

I tried to run the following code: ...
1
vote
1answer
129 views

Equation Simplification in Mathematica

I wonder if the following equation could be further simplified by Mathematica. There are $22$ Integrals involved and many of them are in the range $y_l$ and $y_u$. I would guess that at least those ...
13
votes
4answers
371 views

Replacing parts of a held expression with held parts of another expression

I'm applying the Trott-Strzebonski technique in order to replace inside a held expression. ...
2
votes
1answer
288 views

Finding the optimal teams ranking based on the table of match results

My original question was this: So my task is to score all the possible rankings of the 14 SEC football teams and find the best one, using who won in head-to-head games as the sole criterion (...

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