12
votes
2answers
279 views

Parallelization of distinct array write access from subkernels

I'm working on an implementation of a multivariate FFT, which is (or at least should be) highly parallelizable due to the row-column-algorithm. However, i can't figure out how to implement that. The ...
11
votes
4answers
674 views

Is there a way to increase the smoothness of a cylinder?

I am using Cylinder to produce wide flat disks (in Mathematica 8). This works just fine except that the circular base of such a cylinder turns out to be really just ...
11
votes
1answer
391 views

Map of Specific US States? (Isolated)

My question here is fairly basic, and I'm sure I'm overlooking something basic. I know about CountryData for creating shapes of entire countries, and it works, to ...
11
votes
1answer
367 views

Generating Gelfand-Tsetlin patterns

I am doing some research on some combinatorial object called GT-patterns. They are generated from three parts of data. Two integer, partitions (sequences of weakly decreasing numbers), $\lambda = ...
11
votes
2answers
200 views

ReplaceRepeated seemingly omits some rules

Is there a simple way in Mathematica to prevent rule reordering? Let me give an example: ...
11
votes
1answer
229 views

FindInstance returns Indeterminate in version 9, but not in 8

Here is a trivial system of equations in three unknowns for which FindInstance obtains a solution: ...
11
votes
2answers
426 views
11
votes
3answers
584 views

How do I “start a reference system”?

When I attempt to insert a citation or specify a database to use as a bibliography, I get a message that I need to "start" the "reference system" "manually": I have no idea what a references system ...
11
votes
4answers
818 views

How do I find the degree of a multivariable polynomial automatically?

I have a very simple question which appears not to have already been answered on this forum. Is there built-in functionality that returns the degree of a multivariable polynomial? For example if the ...
11
votes
2answers
284 views

Package found with `Needs`, but not with `ParallelNeeds`

I want to use a self-written package in a parallel computation. However while Needs["mypackage`"] works without problems, ...
11
votes
1answer
377 views

Saving a notebook as a $\LaTeX$ file, with syntax highlighting preserved

How can I save a notebook as a $\LaTeX$ file, while preserving the syntax highlighting (such as input/output boxes)?
11
votes
1answer
499 views

Space-efficient null space of sparse array

I have a roughly 100,000 × 3,000 matrix (as a SparseArray) that I'd like to find the kernel (null space) of. It has about 500,000 nonzero entries, all -1 or 1. ...
11
votes
4answers
285 views

Background Shading in Histogram3D

I am preparing some data for dissemination. I have a series of plots that look like so, using ListLinePlot: The background shading is just being added using ...
11
votes
2answers
678 views

Why is ListDensityPlot unable to plot datasets with extreme ranges

Consider the following dataset: data = Flatten[ Table[{x 10^-9, y 10^-9, x^2 + y^2},{x, -100, 100, 10}, {y, -100,100, 10}] , 1]; If I try to ...
11
votes
3answers
525 views

How to mark an image?

How can I place a mark, like a cross-hair (to suggest "X marks the spot") and a text label associated with it, at a particular position on an image (mine in particular is ...
11
votes
2answers
265 views
11
votes
1answer
335 views

Boosting the performance of expensive NIntegrate by feeding in a cheap approximation of the integrand

I need to integrate an expensive likelihood L[x] over its n-dimensional domain. I know that L[x] is decently approximated by a ...
11
votes
3answers
414 views

Plot on command within DynamicModule?

Suppose I have a DynamicModule with all sorts of controls to set some parameters for a graphics object. ...
11
votes
3answers
360 views

Does AbsoluteTiming slow the evaluation time?

I've started using AbsoluteTiming to discriminate between similar function constructs, but I sometimes feel like it takes substantially more time to evaluate a ...
11
votes
5answers
1k views

Fastest square number test

What is the fastest possible square number test in Mathematica 7, both for machine size and big integers? I presume in version 8 the fastest will be a dedicated C LibraryLink function.
10
votes
2answers
352 views

How do I get Mathematica to return a function call unevaluated?

How do I get Mathematica to return a function call (conditionally) unevaluated? I expect this may use the slightly-mysterious Hold function. As a toy example, ...
10
votes
4answers
257 views

Efficient way of identifying the indices of first occurrences

It seems to me like identifying the first occurrence of unique elements should take about the same amount of time as it takes to delete duplicates. My data sets are much larger than this (...
10
votes
3answers
212 views

Returning multiple results from a LibraryLink function

What is the best way to return multiple inhomogeneous results from a LibraryLink function? Imagine that the result of a single computation is several tensors of different dimensions and several ...
10
votes
5answers
485 views

How to choose three points on the circle so that the triangle is not a right triangle?

I want to choose three points $A$, $B$, $C$ has integer coordinates on the circle $$(x+2)^2 + (y+1)^2 = 25$$ so that the triangle is not a right triangle. But I can not. I tried ...
10
votes
1answer
265 views

Why does Mathematica fail to series expand this simple expression?

I wanted to expand the function $(x+2)^{x+2}$ around $x = -1$, that is, using Series[(x + 2)^(x + 2), {x, -1, 2}] and Mathematica returns the same expression. ...
10
votes
4answers
2k views

Why does Mathematica struggle with solving this equation?

Consider the evaluation of the following expression In[20]:= Reduce[ 1000 * 1.0609^t == 1500, t] ...
10
votes
2answers
1k views

Did Mathematica 9 remove some previously available stylesheets?

Did Mathematica 9 remove some previously available stylesheets? If so, how can I customize a currently available style sheet to be like a previous one or get previous version's stylesheet back? I ...
10
votes
3answers
851 views

Derivatives (divergence, gradient, curl) of interpolated 3D data

How can I calculate a vector derivative (i.e. divergence, gradient, curl) of interpolated data? For sample data, you can use: ...
10
votes
1answer
508 views

Visualize cluster distances in DendrogramPlot

I want to perform a cluster analysis using the HierarchicalClustering package. Is there a way to display the inter-cluster distances in a dendrogram plot? An ...
10
votes
3answers
709 views

One-dimensional heatmap

I want to plot a heatmap of a set of real points of the interval [0,1] - i.e., to display their linear density in the sense of a smoothed histogram. The idea I have come up so far is to use the ...
10
votes
1answer
200 views

Unexpected behavior of Compile, Return and ;

Could somebody explain why test = Compile[{{x}}, Return[x]; ]; test[0.] returns ...
10
votes
2answers
1k views

CUDA and GPU hardware and compatibility questions?

We have iMac desktops and have just begun to parallelize computations across them see: Wolfram Light Weight Grid and parallel computing. This still does not look like it will give us the performance ...
10
votes
6answers
1k views

2D Gaussian distribution of squares coordinates

I would like to imitate the structure of this great painting from Ellsworth Kelly in Mathematica. Yet with all the colored squares in Black and the beige one in white. Below is what I have wrote to ...
9
votes
1answer
113 views

Tracking Initialization

How to track Initialization step by step? Any tricky solution is ok. One condition, x should be ...
9
votes
1answer
136 views

Is this a bug in NIntegrate?

Is this a bug or I missed something? NIntegrate seems to give a different answer for the same integrand when the option ...
9
votes
1answer
398 views

How to solve a stiff nonlinear second-order ode?

I want to solve a nonlinear second order ODE as an initial value problem (IVP). Unfortunately, for certain values of first derivative at starting point I get a stiff-problem. I tried to overtake this ...
9
votes
4answers
328 views

Finding a point from a set of contours such that it is nearest to a given point

I have several contour lines and one point. How can I find a point in one of those contour lines which is nearest to the given point? ...
9
votes
1answer
122 views

Named string patterns in Alternatives, why does it depend on order?

When using the same name for part of patterns inside Alternatives how come it behaves differently for strings than in normal patterns? ...
9
votes
3answers
1k views

Guidelines on giving readable names to variables [closed]

I know that one cannot use underscore to a variable name, like degree_of_The_First_Polynomial. But for a long variable name, it ...
9
votes
3answers
239 views

substitution rules excluding subscripted variables

Suppose I have an expression containing p,Subscript[p,1],Subscript[p,2],etc. I want to ...
9
votes
5answers
297 views

How can I remove matching sublists from my list?

I want to use DeleteCases (or any appropriate function) to remove elements of a list, which in turn are lists of fixed size. The rule I wish to apply is that any ...
9
votes
1answer
249 views

PlotMarkers doesn't inherit PlotStyle when first argument to Graphics isn't a list

Could somebody explain, why Circle does not inherit the PlotStyle of the plot when used as ...
9
votes
1answer
147 views

Algorithm used by IsomorphicGraphQ

I'd like to know which algorithm is used to test if two graphs are isomorphic?
9
votes
2answers
785 views

Coloring each face of a Cuboid with a different color

Is there a way to color each face of a Cuboid with a different color? I looked in the help but couldn't find anything. I found this Coloring the faces of a 3D ...
9
votes
1answer
239 views

How do I determine astronomical transit times?

Mathematica, through the "legacy" Scientific Astronomer package, used to have the ability to easily determine accurate transit times of astronomical objects simply, with ...
9
votes
1answer
535 views

Efficient export of complex graphics to PDF

So I have 2D plot, made with DensityListPlot. Mathematica just cannot export them properly to PDF, so what I want to do is 1) export the plot itself, without axes, labels, etc, as a jpg image, and 2) ...
9
votes
5answers
272 views

How can I highlight one function in the Plot of a list?

I've got a Plot of a list of functions from this previous question of mine. ...
9
votes
1answer
148 views
9
votes
3answers
3k views

Expressing a decimal as a fraction in lowest terms

How can I express a decimal such as 0.1845095405274387 as a fraction in its lowest terms?
9
votes
1answer
666 views

CUDALink not working on Mac OS X

On my MacBook Pro, I have a CUDA enabled video card, yet Mathematica does not seem to recognize this. For example, following the CUDALink Setup, I get ...

15 30 50 per page