All Questions

3k views

NonlinearModelFit does not find a good fit

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

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 $\{t,x,y,z,r,\phi_1,\... 1answer 120 views Why does a heavy background slow LocatorPane from updating, even if only the locators are Dynamic? I'm having some trouble getting a dynamic plot to operate efficiently, and I think I've tracked down at least part of the problem to some pretty weird behaviour on the part of ... 1answer 542 views Import invocation fails with Get::noopen : Cannot open JLink error The following function call fails when I invoke it in a fresh Mathematica session: ... 2answers 275 views MathLink Graphical Output (Plots) to File In a custom Mathematica frontend based on MathLink I try to make use of plots produced in Notebooks. The idea is to write them to files whenever they get produced. According to C-code snippets I ... 1answer 97 views Using Derivative with list in curly brackets I'd like to make a formula for a sum containing Derivative where the number of arguments in the latter depends on an input parameter n. Also involved is a list <... 2answers 162 views Why the Block command does not forget the$ContextPath variable

I do not understand this behavior: ...
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 $a_b$ ...
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 ...
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 ...
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. ...
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 <...
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 ...
2k views

I evaluate ...
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 ...
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 ...
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 ...
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:)
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: ...
108 views

Getting error FullSimplify::infd: … simplified to ComplexInfinity

I tried to run the following code: ...
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 ...