For questions specific to Version 7 of Mathematica.

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20
votes
1answer
229 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: ...
15
votes
4answers
1k views

What is the right way to rotate an array?

Suppose I have an array, not necessarily square: a = $\left( \begin{array}{ccc} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array} \right)$ I want to rotate it like one ...
13
votes
2answers
424 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 ...
12
votes
6answers
548 views

Sort+Union on a list

Probably this is too trivial question for this forum but for some reason I am not getting it on my Mathematica 7 so far. I have a list ...
12
votes
2answers
330 views

Internal “Periodical” functions in version 7

In version 7 there exist these Internal` context functions: ?Internal`*Periodical* ...
11
votes
2answers
518 views

backward compatibility

When producing or enhancing code, it is tempting to use recent new primitives of Mathematica introduced in version 7 and 8, but for library code or in preparation or future version change in ...
9
votes
3answers
411 views

Why does Hash return different values in Version 7?

This function does not work correctly for me. The generated Gravatars do not match the ones actually produced by using the corresponding address. The problem was traced to differing output from the ...
8
votes
1answer
115 views

$InputFileName backwards compatibility

What would be a good replacement for $InputFileName (which has been added recently to Mathematica 8) to achieve backwards compatibility with let's say M6 and M7? I ...
8
votes
2answers
2k views

Legends in combined Plot and ListPlot

I have a set of data ...
8
votes
2answers
510 views

Problem with ContourPlot3D

The following line works fine: ...
7
votes
4answers
296 views

Unexpected behavior from GatherBy in version 7

I have come across what appears to be a bug in GatherBy. It appears similar to the problem of using Table[Random[], {1000}] in ...
7
votes
3answers
487 views

Plotting a 3D list causes kernel to crash if x and y axes have vastly different scales

I have access to two versions of Mathematica, version 7.0.1 on Linux and version 8 on Windows. When I try the following two lines on version 7, the kernel quits when it tries to plot. In version 8 ...
7
votes
1answer
943 views

Mathematica: Label specific vertices in GraphPlot

How can I label particular vertices in GraphPlot? And have the arrows space out accordingly, for the width of the label? I have Mathematica 7, but I think this question applies to all versions. ...
7
votes
2answers
269 views

Tick marks shrinking with ImageResolution [duplicate]

High resolution PNG export is handy for print quality plots, however tick marks are not scaling properly. Does anyone know a solution or a work-around, preferably for M7 (on Win7)? ...
7
votes
1answer
99 views

Bug in GeneratingFunction?

According to the documentation GeneratingFunction[a[n],n,x]==Sum[a[n]x^n,{n,0,Infinity}] However, for $a_n=1/(n+2)$ I obtain ...
6
votes
3answers
497 views

How to randomly erode a 3D distribution of points with Mma 7.0?

Suppose we have a 3D distribution of points, like the spherical ball example below : ...
6
votes
1answer
346 views

PrintTemporary in ParallelTable

I thought of a possible answer to Monitor doesn't work with ParallelTable but it doesn't work as I hoped it would. This accumulates print cells instead of deleting them as intended. Can it be ...
6
votes
0answers
151 views

Mathematica 7: “LessEqual::nord:” error when using NMinimize on a real function

I encounter a problem (Mathematica 7) similar to Strategies to avoid LessEqual::nord in NMinimize? but the advised strategies don't work for me. Also, I get different results with different ...
5
votes
1answer
197 views

Sorting an Array with words in different languages

Array consists of words of different languages. I need to sort elements in reverse alphabetical order and make a list of elements, which consist of english letters. Example of array which consist of ...
4
votes
1answer
132 views

Exported animated gif with matrices will not work?

I want to export a list of matrices as a gif so that they will appear one after another 2 seconds apart. I've tried the following but when I open it up it only does the first two matrices and I have ...
4
votes
1answer
95 views

Is it possible to enable syntax highlighting for \[Function]?

This is a bit of a long shot but I am wondering if it is possible to enable syntax highlighting in a function defined with \[Function] without resorting to anything ...
4
votes
2answers
236 views

How can this DivisorSigma code be made fast?

Since Project Euler problems are now fair game for questions I have a question of my own. A certain problem* states: For a positive integer n, let σ2(n) be the sum of the squares of its ...
4
votes
1answer
256 views

Sporadic bug in Mathematica 7.01.0 MatrixPower and/or Eigensystem functions on floating-point symmetric matrices with repeated eigenvalues

Note: From the comments submitted below by other StackExchange users it appears that this apparent bug was fixed sometime after version 7.0.1. I asked a vague variant of this question a few days ago, ...
4
votes
0answers
68 views

Error with String patterns producing Removed[“$$Failure”]

While working on How to capitalize the first letter of each word in a string and trying to understand why certain characters were not considered letters I tried this: ...
4
votes
0answers
240 views

NullSpace[_, Method->“OneStepRowReduction”] is sometimes wrong; how can I work out when this happens?

(This is on MMA 7.0.1.0 on OS X) I've just found a large matrix m for which NullSpace[m] and ...
3
votes
3answers
281 views

Colorize a 3D distribution of points according to density

Suppose we have some random 3D distribution of points. I'll use the spherical ball defined below as an example and a starting point for the discussion here : ...
3
votes
1answer
78 views

Bug with LinearProgramming on Integers?

With Mathematica 7: LinearProgramming[{1, 1}, {{0, 0}, {1, 1}}, {1, 1}, Automatic, Integers] gives wrong result {0,1}. But ...
3
votes
0answers
94 views

An recurrence equation that can be solved in version 7 but not in version 8

A friend of mine showed me this code sample: RSolve[{a[n] == a[n - 5] + 1, Sequence @@ Table[a[i] == 1, {i, 5}]}, a[n], n] // Timing It's solved by version 7 in ...
2
votes
3answers
77 views

Reduction of repetitive calculations in Table

If I generate two tables inside a function which are function[n_, x_, y_]:=( table1 = Table[i* x/n^x, {i,1,n}]; table2 = Table[i* y/n^y, {i,1,n}]; ) where ...
2
votes
1answer
114 views

Plot: How set markers in plot in front of axes

I draw a plot using ListPlot. But I noticed that PlotMarkers are 'covered' by the axes; see example below: I was trying to ...
2
votes
1answer
183 views

ListPlot - plotting values with different range

I have three tables: L, S and U. In first table I have values from range (0,1), in second ...
2
votes
1answer
635 views

How to take the derivative w.r.t. an arbitrary function?

EDIT: The answer posted by @Jens works for built-in functions only. However I'm starting to wonder if this is related to my Mathematica install somehow. I have version 7. Here is an example in the ...
2
votes
1answer
145 views

How to extract the bin width from a Histogram made with an automatic binning method?

I am using the Scott binning method with Histogram and Histogram3D to plot some data. How could I find out the bin width chosen ...
2
votes
1answer
60 views

Error with comments inside and expression

I found this strange parsing error with comments inside of an expression in Version 7. And example is {{1, x}, {1, y} (* {1, z (= 5+6)} *)}; It occurs depending ...
2
votes
2answers
146 views

How can I style a TabView?

I have been trying to style a TabView like in the examples on the Wolfram CDF site, where they have custom sizes and backgrounds with images or gradients, but I am ...
2
votes
1answer
193 views

Export to mat file does not work

I use this command from the Mathematica documentation center Export["1.mat", {"t" -> {{1,2,3}},"u" -> {{4,5,6}}}, "LabeledData"] to save data as mat file ...
2
votes
1answer
148 views

Version 7 and 8, different behavior of NSolve. Is it reproducible?

I noticed the following difference, and I wonder if it's a problem of my system or the results difference is actually due to the two different versions ...
2
votes
0answers
78 views

Det and MatrixRank freezes on SparseArray with nonzero default value

Why does the following simple code never come to an end (at least with version 8) n = 5; mat = SparseArray[{i_, i_} -> 1, {n, n}, -1/(n - 1)]; MatrixRank[mat] ...
2
votes
0answers
371 views

Simple contour integral with a parameter gone wrong

I run into the following problem, I tried to evaluate a very simple integral: Assuming[ a > 0 , Integrate[Sin[a*s]/(s - I)^2, {s, -Infinity, Infinity}]] ...
1
vote
2answers
239 views

How to blend some colors on a curve

I need to define a color gradient on a 3D curve, but I'm having some problems with this. Suppose we have a 3D curve defined as a parametric function of some real variable ...
1
vote
2answers
146 views

Converting polygon to graph in V7

I've unsuccessfully tried many ways of converting polygon points into a graph using Mathematica 7, and I am frustrated. I looked at this post, but it doesn't work: ...
1
vote
2answers
46 views

How to fix the order in which text appears in an axis label (V7) [duplicate]

One of the AxesLabel is "$:\text{log}|\Phi8b(u)|\color{Red}{\text{Red}}$". Question: How to make it like: "$\color{Red}{\text{Red}}:\text{log}|\Phi8b(u)|$"?. My Mathematica commads: ...
1
vote
1answer
487 views

ListPlot doesn't shows all points [closed]

I have a table: p1 = Table[(Binomial[2000, k]*StirlingS2[1386, k]*k!)/(2000^1386), {k, 1, 1386, 1}]; I used ListPlot[p1] ...
1
vote
1answer
77 views

Use Compile to speed up evaluation

I have read, that using Compile command can speed up evaluations in mathematica. I have a mathematical expression, which I evaluate using following command: ...
1
vote
2answers
159 views

Error changing edge thickness in a GraphPlot

I'm having some problems with the Mathematica graphics inspector. I want to make a graph with the following code: ...
1
vote
1answer
218 views

Version differences in Parallelize

I am having a problem which I guess is due to version difference. I have to generate a list of unitary matrices, which I can do easily. However I came to know about ...
1
vote
1answer
67 views

Warning and Errors during Compile

I defined a compiled function cf = Compile[{{x, _Integer}, {n, _Integer}}, z = (n^x); Binomial[n, #]* StirlingS2[x, #] *(#!)/z & /@ Range[x]]; and I ...
1
vote
1answer
158 views

Spacer and Text in Graphics going Awry (in Mathematica 7)

Use of a vertical Spacer in justified text inside a graphic isn't working as required. The result in the green box looks right, but when this is placed in a ...
1
vote
1answer
101 views

TextCell going awry due to ImageResolution (in Mathematica 7)

Can anyone see how to fix this text display? The example is from a larger project. I need to export the graphic at high resolution, but the text is going wrong. ...
1
vote
1answer
56 views

Place legend without border above the plot

I use Mathematica 7.0 and as far as I know, there is not method PlotLegends, only PlotLegend. I want to set my legend - without background, shadow and frame - above my plot, as in the example belowe: ...