45
votes
2answers
2k views

Once more on object orientation in Mathematica: does it have to be so hard?

Recently I came across a set of problems which would be solved most easily within an object-oriented approach. I first attempted to solve them by other means, but found the complexity of the code ...
3
votes
1answer
156 views

What is causing a type error when trying to modify Mathematica state from a function linked with LibraryLink

I've managed to reduce my problem to a very simple C program: ...
2
votes
0answers
126 views

Smooth Max and Abs

I'm trying to implement smooth approximations of Max and Abs functions. Moreover I want the functions to map element-wise on tensors. Here's my code. ...
2
votes
1answer
95 views

How do I make an EventHandler non-responsive to MouseMoved after a mouse click?

Consider the following code. After evaluating it, when I move the mouse over the output text, it prints 1, and when I click the mouse on ...
3
votes
0answers
484 views

how to associate a metric for tensor contraction operations?

I see that Version 9 now has some built in tensor support (which was missing back when previously asked How to represent and manipulate abstract indexed vector (or tensor) expressions?). The docs ...
2
votes
1answer
235 views

is it possible to modify BaseStyle of Manipulate dynamically?

I can't decide what is a best color for the background for a Manipulate I am writing. So, I thought since this is Manipulate, why not make this part configurable as well, so one can change the RGB ...
5
votes
4answers
1k views

How to find the sum all even numbers of this sequence?

I have a sequence $(u_{n})$ $$u_1= 1, \quad u_2 = 2, \quad u_3 = 3, \quad u_{n}= -u_{n-3} + 3u _{n-2} +2 u_{n-1}, \quad \forall n \geqslant 4.$$ I want to list the first $20$ terms of this sequence ...
3
votes
2answers
307 views

Pasting external PDF vector graphics without losing ability to export them

As in previous versions, Mathematica 9 on Mac OS X (10.7.5 here) still has a problem with pasted PDF graphics that were copied from external applications such as ...
2
votes
2answers
301 views

FullSimplify inconsistency

I'm pulling my hair out with this one. I have two complex functions f and g, ρ is real. ...
17
votes
6answers
1k views

How do I make an image “nearly” black and white?

Using the following code, I downloaded an image from the web and adjusted the image to obtain the "negation" of the image: ...
4
votes
2answers
248 views

What causes this strange convergent sum?

N[Sum[1/(x^2 + 1), {x, 1, Infinity}], 5] N[Sum[1/(x^2 + x + 1), {x, 1, Infinity}], 5] 1.0767 0.79815 + 0.*10^-6 I What causes the strange number?
14
votes
3answers
602 views

How can I improve my code for drawing a tree?

This code draws a tree, but it's not in the functional style. ...
11
votes
9answers
4k views

How do I extract a number from a string?

I want to extract the number from an alphanumeric string. This is what I tried: StringTake["thiru3", {6, 6}] The result I got is ...
30
votes
1answer
356 views

Quickly look-up usages, options and attributes of symbols

When I'm writing code in the front-end, I find myself very often looking up the list of options of a symbol over and over again in the documentation center. In most cases you find there a list of ...
0
votes
1answer
196 views

Preventing Grid from resizing when the item height is increased

I created a grid of size 200,200 and placed a button in it of size 200×200. ...
0
votes
1answer
263 views

How to express endogenous variables in terms of exogenous variables?

I have 11 endogenous variables (RD, NR, WR, Q, NQ, R, L, W, NU, C1, C2) and two exogenous variables (EE, K). I'm trying to find $RD = f(EE, K),\, NR = f(EE, K),\, ...,\, C2 = f(EE, K)$. Hence, I ...
4
votes
1answer
146 views

Why are some equal expressions more equal than others?

n1 = 1/3 (2 + (-Sqrt[3] + 2 Sin[(2 π)/9])/(Sqrt[3] Cos[π/9] - Sin[π/9])); n2 = 1/2 + Sin[π/18]/(3 Cos[(2 π)/9] + Sqrt[3] Sin[(2 π)/9]); n3 = 2/3 (1 - Cos[4 π/9]); ...
5
votes
3answers
427 views

How do I find the amount of free space on disk?

I know a workaround, where one calculates sizes of all files and then you subtract this from your default space, but is there any direct way to do it? Simplicity and speed are important. There's the ...
8
votes
1answer
3k views

Is there an option to change the space/distance between tick labels and axes labels for plots?

In an attempt to squeeze more plots and controls into the limited space for a demo UI, I am trying to remove any extra white spaces I see. I am not sure what options to use to reduce the amount of ...
2
votes
2answers
658 views

NDSolve problems of convergence

I have a big function that I have to maximize, so I have to evaluate some equation with thousands of different values of the parameter. But the FindMaximum returns me many errors. I have traced the ...
11
votes
1answer
1k views

Is there a “No Units” (i.e., dimensionless) unit?

I would like to be able to call the Quantity function with a null unit so that it returns the original dimensionless value. For example, ...
18
votes
3answers
727 views

Create an adaptive amount of local variables for error propagation

I intend to write a function which calculates the result and the error for any formula with any amount of variables using the Gauß Error Propagation. The error $\mathrm{d}R$ for a function $R(a,b,c)$ ...
5
votes
3answers
171 views

All values for a function with two arguments without Outer

Given two lists $l_a = \{a_1, a_2, a_3\}$, $l_b = \{b_1, b_2, b_3, b_4\}$ and some function $f$ accepting two arguments, how can I produce a list of all values $f(a, b)$ for $a\in l_a$ and $b \in l_b$ ...
6
votes
2answers
204 views

Can I redefine a list as a set of variables?

Suppose I have a list mydata = {3, 14, 15, 92, 65} and in some cases I want to manipulate it as a list, like for reading from and writing to a file, or for ...
1
vote
2answers
259 views

How to make a Tooltip display dynamic based on a parameter value?

If k=3, then I would like the following to say "Sine Curve, k=3" when you hover over the output of the Tooltip command: ...
8
votes
1answer
221 views

Transformation rule on a list of non-negative integers

I am trying to create a transformation rule that takes a list of non-negative integer values of any length, finds a non-zero entry in the list, adds 1 to all preceding numbers, subtracts 1 from the ...
7
votes
1answer
1k views

Dynamic Graph visualization

I'm working on a C++ library that will be used to construct and study certain graphs (as in a set of connected vertices, not a function plot). These graphs will be dynamic in nature (and can ...
-1
votes
1answer
444 views

Problem with #1's in DSolve

I've entered the following functions into my notebook, but the solution to them contains #1's that I can't seem to make any sense of. The functions are: ...
10
votes
4answers
2k views

Creating an animation illustrating the time-evolution of a pre-computed orbit

As the title says, I would like to use Mathematica in order to create an animation depicting the time-evolution of a three-dimensional (3D) orbit. To begin with, I have an ASCII file which contains ...
0
votes
1answer
411 views

importing and manipulating data file

I have a large text file containing numeric data of 1000 groups each of 200 lines. The lines are unsorted. There is a 9 line header at the beginning of each group, i.e., 209 ⨉ 1000 lines altogether. ...
-2
votes
1answer
120 views

Can Depth be used as an equivalent for MatrixQ?

Given an expression x, are the following two statements interchangable with no exceptions? Depth[x] - 1 == 2 ...
1
vote
1answer
351 views

How to Chop correctly?

I want to count degeneracies in a list called spectrum. The list contains numbers of double (~ 15digits) precision. So it makes no sense if the noise below this ...
0
votes
1answer
267 views

Mathematica: how to make Z transformation of data from CSV File

I have a discrete Signal in my CSV File and I want to transform it in Z. I import the data with Data=Import["T:/data.csv","CSV"] and I try to transform it ...
10
votes
1answer
557 views

Number format in Legend Labels

I would like to use the usual (new and nice) BarLegend[] with something like BarLegend[{"LakeColors", 1/10000 {-2, 2}}] which ...
12
votes
4answers
491 views

How to remove ticks?

I wanted to remove the Ticks in my coding but i can't. Here when i try to remove the Ticks the number also gone. I need numbers ...
0
votes
1answer
95 views

How should I make a label?

This is my code for making a label. I used a Button expression to build it. Is there a better way to make a label? My objection to doing it this way is that, when I ...
1
vote
2answers
1k views

AxesLabel in RegionPlot does not work

I simply want to add labels to the axes without using the Drawing Tools menu, I tried this without success: ...
2
votes
1answer
599 views

If-statement does not evaluate if condition is true [duplicate]

Possible Duplicate: How to avoid returning a Null if there is no “else” condition in an If contruct I know there are other ways to solve this problem. Just because I'm curious I tried: ...
2
votes
3answers
163 views

How to change FieldSize to be the same as dropdown menu width in PopupMenu?

I've tried the following code to change the FieldSize but I can't make it equal the actual value of MenuSize and I tried to ...
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
2answers
451 views

How can I control the behavior of a Manipulate with check boxes and radio buttons?

I've been stuck for a long time on this problem, and I really would appreciate if somebody helps me move in the right direction. I have two functions and each can take one of two forms. I am ...
18
votes
1answer
656 views

How to get a plot generated by R returned in an output cell?

It seems we'll never have built in two axis plots and list plots in Mathematica but you can make them in R. ...
20
votes
4answers
1k views

Time-series decomposition in Mathematica

I'm studying time-series in R with this book, and there is a nice command in R that creates decompositions. Inside Mathematica 9 the command can be executed as: ...
7
votes
6answers
405 views

The locations of (row-wise) minimum elements in a list

I have a list representing a 2D matrix, such as this 3 ⨉ 2 one: {{2.1, 1.01}, {0.01, 7.2}, {7.8, 2.0}} Does anyone know how to find the minimum of each row, ...
5
votes
3answers
312 views

More structure in Source Code/Notebooks

Mathematica is great for small and quick projects and has a great syntax. However as soon as a project grows I run into trouble. How do you scale and maintain projects in Mathematica? What is beyond ...
5
votes
1answer
268 views

How can I download price information for multiple stocks at once?

I have a list of stock tickers. Is it possible to download price information over a period of time all in one go, or download other types of information across multiple stocks in one go?
12
votes
2answers
261 views

Why does DominantColors keep shuffling the order of the results?

This graphic is produced by running DominantColors (new in Mathematica 9) with different values, using the Lena image as the source: Each row is a list of the ...
6
votes
3answers
255 views

How to calculate this sum?

I want to find the sum $$S=f\left(\dfrac{1}{2012} \right) +f\left(\dfrac{2}{2012} \right) +\cdots + f\left(\dfrac{2011}{2012} \right), $$ where $$f(x) = \dfrac{4^x}{4^x + 2}.$$ I tried ...
16
votes
4answers
1k views

Is there a shortcut to select all cells above the current cursor position?

Is there a command / menu entry / keyboard shortcut to evaluate all cells above / up to the current cursor position? I have the feeling I am missing something elementary here... Addendum: In fact, it ...
2
votes
1answer
253 views

3D plots wrongly displayed when using GraphicsRow in Linux

I get an incorrect vertical offset in 3D plots when using GraphicsRow in Mathematica 9 (Linux - Ubuntu 12.04). When displayed by itself, the plot is fine. Here's an example: ...

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