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31
votes
2answers
900 views

Variable naming changes everything

I am having a rather unusual problem I do not understand with Mathematica where renaming one of the variables of my function causes the function to stop "working". Here is the example of the code ...
30
votes
1answer
845 views

Transferring a large amount of data in parallel calculations

This question is inspired by one of @whuber's answers Consider the following code: ...
28
votes
3answers
776 views

No warning when extrapolating with Plot

One of the most annoying "features" of Mathematica is that the Plot family does extrapolation on InterpolatingFunctions without ...
26
votes
7answers
1k views

ColorData[“VisibleSpectrum”] is wrong?

I am trying to visualize the visible spectrum using the built-in ColorData["VisibleSpectrum"] function which "colors based on light wavelength in nanometers". But I ...
26
votes
2answers
675 views

DeleteDuplicates not deleting duplicates

It is not surprising that DeleteDuplicates[{5,5.}] returns {5,5.} because DeleteDuplicates ...
25
votes
2answers
731 views

Strange ::usage behavior in v9

Note: This is fixed in 9.0.1. Something has gone wrong with usage in Mathematica 9. Would someone tell me how to fix it? I define a function ...
24
votes
2answers
631 views

Template completion

In version 8, if one evaluates test::usage="test[x,y]"; then types test, then shift-cmd-k (or shift-ctrl-k), a template ...
24
votes
0answers
561 views

What calendar is Mathematica using for dates in the distant past?

It appears that Mathematica treats all dates as proleptic Gregorian dates by default, a hypothesis that can be easily tested by using AbsoluteTime to compute the ...
22
votes
2answers
333 views

eigenvector bug?

I have a fairly simple $3\times3$ complex matrix, $$ M=\left( \begin{array}{ccc} \frac{7}{2}-\frac{i}{2} & -1+i & \frac{1}{2}+\frac{5 i}{2} \\ -1+i & 5+i & -1+i \\ ...
20
votes
4answers
773 views

An apparently “simple” limit?

Let $c$ and $h$ be real values. I was using Mathematica to compute the limit $(h \rightarrow \infty)$ of the following expression: $$ \frac{\left(h^2 +c^2 h^2 + \sqrt{4 h^2+\left(h^2+c^2 ...
20
votes
2answers
1k views

Debugging memory leaks

I've written my incredibly complex, incredibly elegant analysis function, that works great on small test data. But when I run it on my real (bigger) data set it keeps running out of memory. It turns ...
20
votes
1answer
214 views

M9 performance regression for Fold?

I noticed an over 10x performance drop on Mathematica v9.0.1 (as Oleksandr R. commented, also v8) compared with v7.01 for this code: ...
19
votes
2answers
261 views

Plotting a defined function gives different results from plotting the function directly

Consider the following piece of code: function[t_]:=Exp[-9 t^2]; LogLogPlot[{function[t],Exp[-9 t^2]},{t,.01,100}] I expect the two plots to exactly overlap each ...
18
votes
2answers
268 views

Negative probability?

I am trying to get the sum of the squares of seven random variables, all uniformly distributed. This is what I tried. ...
17
votes
2answers
266 views

Graphics elements do not line up perfectly in exported PDFs

Graphics elements do not always line up perfectly in exported PDFs using "Save As..." method. Take, for example: ...
17
votes
3answers
456 views

Memory Leak in Frontend - anyone know a workaround?

When using Rasterize on a Graphics expression composed of many differently coloured Graphics objects memory is allocated in the frontend which is then not released or reused when a similar graphic ...
17
votes
1answer
367 views

Incorrect result from Integrate

I attempted to calculate the following integral: ...
17
votes
2answers
461 views

Have I found a bug in Integrate?

The following command gives 0 in Mathematica 9.0.1. ...
16
votes
3answers
265 views

Error changing Dataset using Part

In the new guide Computation With Structured Datasets we can find this part, on how to change a Dataset But if we create a Dataset like: ...
16
votes
1answer
497 views

When importing GIF animation, how to find the correct list of “DisplayDurations”?

When importing GIF animations with variable frame durations, the settings for "DisplayDurations" are not recovered correctly. As an example, I'm using the movie from this earlier question: Here I'm ...
16
votes
1answer
382 views

How to fix broken InterpolatingFunction?

I have an InterpolatingFunction based on irregularly-gridded data, like this: ...
16
votes
2answers
732 views

How to compute the inverse CDF properly?

Note: this has been fixed in version 9. I want to compute the CDF and inverse CDF of the hyperbolic distribution: ...
16
votes
2answers
556 views

Exporting a dashed plot with a color gradient to a vector graphics format ruins the dashing

When exporting a dashed plot with a color gradient to a vector graphics format such as EPS or PDF, the dashing is partly ruined. For example, this command: ...
16
votes
1answer
278 views

Specifying non-conflicting PlotTheme options

I am trying out Mathematica 10 on https://programming.wolframcloud.com. $PlotTheme interested me a lot because it finally produces nice plots (probably) without the ...
16
votes
1answer
230 views

Bug in RepeatedNull?

RepeatedNull appears to be buggy (versions 8.0, and 9.0). Define f as follows: ...
16
votes
1answer
257 views

Kernel inexplicably hangs if I define a pure function without suppressing output

Save any unsaved work before trying as it may crash Mathematica and other programs by filling up the memory! In v9.0.1.0 on OSX 10.8.5, if I start a new session and define two functions ...
16
votes
1answer
661 views

Bug in Solve (Mathematica 9)

Just came across the strangest bug under both Mathematica 9.0.0 and 9.0.1. If one enters: Solve[m == p Sin[x] && -Pi/2 < x < Pi/2, x] ... then ...
15
votes
3answers
384 views

How can I set Grid alignments using numbers?

There is an example in the Alignment documentation (it also appears in the Grid documentation): ...
15
votes
1answer
739 views

How to export and import Graphs with additional data?

I'm trying to export and then later import graphs with additional data added such as VertexLabels and EdgeLabels. When I export ...
15
votes
2answers
841 views

Why does Mathematica give the wrong answer when integrating?

I integrate Integrate[Exp[I Cos[b - c]] Cos[b], {b, 0, 2 Pi}] Mathematica gives: 2 I Pi BesselJ[1, 1] Which is indepedent ...
15
votes
2answers
254 views

Upon PDF export, edgeless rectangles do not tile perfectly, and corners may be cut. Is this a bug?

Note: this problem is no longer present in version 10. Exporting the following as a PDF file ...
15
votes
1answer
325 views

Why does LogLinearPlot sample its argument outside the specified domain?

I experience a weird bug in the function LogLinearPlot. If the input is an interpolation function, such as the one created like this, ...
15
votes
2answers
450 views

Pattern issues weird warning

Take for example head[b_[PatternSequence[_, _]]] := 9 I know this example serves no purpose as is. It also happens in useful examples such as ...
15
votes
1answer
434 views

How to work with characters from CJK Unified Ideographs Extension B correctly?

Background: Recently I'm trying to deal with some Chinese characters which belongs to the CJK Unified Ideographs Extension B block. The motive comes from some further interest following a former ...
15
votes
1answer
307 views

Kernel crash after idle in version 10.0

In version 10.0, when I leave the Mathematica section idle for some time (of order an hour), the kernel quit automatically. The syntax highlighting is gone and the variables that has defined before ...
15
votes
1answer
359 views

Quiet doesn't work with FindRoot when using Brent method

The following has no solution: FindRoot[x == 1, {x, 0.25, 0, 0.5}] And Mathematica correctly warns us: FindRoot::reged: The point {0.5} is at the edge of the ...
14
votes
4answers
230 views

Unexpected dots from Line

I have noticed cases where Line produces dots in a graphics object when I think it shouldn't. The first of these is: ...
14
votes
1answer
281 views

Adding three integer sparse matrices is very slow. Adding only two is fast

Adding more than two sparse matrices in one step in Mathematica 9 is very slow (in fact I couldn't even wait for it to finish). Here's an example. Let's generate a large sparse matrix: ...
14
votes
1answer
330 views

Why do Arrowheads interfere with ImagePadding?

Bug still present in version 10 under Windows. In a recent posting, Belisarius solved a problem related to the display of arrows on the x and y axes by setting ...
14
votes
1answer
1k views

Version 9 Blue Screen or Self-Test Error on Windows 7 64-bit

Update There is now an official response from Wolfram Support on this issue. Having recently installed Mathematica version 9 64-bit on Windows 7, I keep running into Self-Test Errors evaluating ...
14
votes
1answer
219 views

Mathematica 9 cannot solve a difference equation that Mathematica 8 can

Consider RSolve[{a[n + 1] == 2 a[n] + n (1 + 2^n), a[1] == 1}, a[n], n] Mathematica 8 can solve this quickly, but Mathematica 9, even after being allowed to run ...
13
votes
4answers
427 views

HoldForm doesn't hold form

In Mathematica version 10, HoldForm no longer produces the same results as in version 8 (edit: I only have versions 10 and 8 installed, so can't compare to version ...
13
votes
4answers
648 views

Mathematica gives wrong result while Wolfram|Alpha is correct

Why does Mathematica and Wolfram|Alpha give different results based upon the same code? I know Wolfram|Alpha's 7.85 is correct.
13
votes
1answer
278 views

High memory use while exporting a BMP

Something mysterious is going on when exporting images. I'm using Mathematica 9.0.1 on Windows 7 (64 bit), and find that the memory use is excessive when exporting to a bmp. But it doesn't happen ...
13
votes
3answers
2k views

Mathematica script - passing command line arguments

When using Mathematica script #!/usr/local/bin/MathematicaScript -script Print[$ScriptCommandLine] and running it with some arguments: ...
13
votes
2answers
359 views

Problem importing URL with Greek characters

I'm considering buying a car. So I thought why not make a web-crawler in Mathematica to pile-up car data? Brilliant idea. Then I found this Greek website, gocar.gr, which just so happens to have all ...
13
votes
1answer
335 views

RandomVariate returns values outside the support of a PDF

Let $X$ be a random variable with pdf: dist = ProbabilityDistribution[1/(Abs[x]*Log[Abs[x]]^2), {x, -E^-2, E^-2}] Here are some pseudo-random drawings from it: ...
13
votes
2answers
417 views

How to embed an image into a string?

Note: The bug described in the post is in Mathematica 9, and has been fixed in 10.0. The documentation for String contains the following statements: Strings ...
13
votes
1answer
611 views

Adding ContourLabels changes contour colors?

I have an array s5 I want to plot using ListContourPlot ...
13
votes
1answer
246 views

Problems with images caused by which stylesheet is used

Update This looks now like it was a bug in Mathematica version 8, because everything works as expected - at least for this minimal example - in version 9. (As an aside, I couldn't seem to find ...