# All Questions

353 views

### FindInstance with a Diophantine equation seems to go on forever

I tried to find a non-trivial integer solution to the equation $$2012^2=a^2+b^2+c^2+d^2+e^2$$ with Mathematica but the computation takes minutes; I might be doing something wrong. ...
344 views

### How to save ChemicalData queries so that they are available immediately on notebook load?

If I put some viscosity (or density, ...) lookups in my notebook, such as: ...
364 views

### How to load thumbnail, not image?

Is there any way to import only the thumbnail of an image instead of the full image? I frequently work with lots of images and it would be nice if the contents of a directory could be quickly ...
593 views

### How to set row height in Grid?

I always thought that Grid (and the underlying GridBox) and the general handling of tabular objects is a bit weird in ...
275 views

### Why does Assuming[x > 0, TrueQ[x > 0]] return False?

Assuming[x>0,TrueQ[x>0]] should, as I understand it, test TrueQ[x>0] after assuming ...
2k views

### Extract values for ViewMatrix from a Graphics3D

Under More Information in the help page of ViewMatrix the following entry can be found With the setting ...
325 views

### How one can programmatically transform a text into Gothic, DoubleStruck, or something similar?

In the pieces of text created programmatically I would like to be able to fix that the text is done in one of the styles available in the special characters palette, such as Gothic. It may be useful ...
218 views

### How to set a rule in pattern matching to change a string from one form to another

I want to define a rule that will change a particular type of string to another form. For example:- a string having ...
4k views

### Using PlotLegends with Show messes up the graphics

I have already obtained the plot that I want but am having trouble legending the graph correctly. ...
598 views

### How to replace the style of the inline cell in a StyleSheet

I would like to change a StyleSheet in such a way that any text that is typed into the inline cell (the one created by Ctrl+9) is shown in a different font (e.g. the font of my choice). At present I ...
759 views

### Does $x>0$ imply that $x\in\mathbb{R}$?

Let’s assume I input Assuming[x > 0, expression] Is it assumed by Mathematica that $x$ is a real number? Or that the real part of $x$ is positive? Something ...
6k views

### Calling Correct Function for Plotting DiracDelta

I am wondering what is the correct function in Mathematica to plot the true impulse function, better known as the DiracDelta[] function. When using this inside of a ...
197 views

### NumberOfSpanningTrees command not working correctly

I am attempting to use the Combinatorica NumberOfSpanningTrees command for all n-cycle graphs from 3 to 30. I am trying to get a ...
1k views

### NMinimize with defined function call getting error NMinimize::nnum

I want to call the NMinimize function for my own defined calculations but I got an error. Below is a simple example. ...
2k views

### What is a Mathematica packed array?

A simple sounding question with a few sub questions: What is the difference between unpacked vs packed array? Are packed arrays more space efficent, how much so? Are packed arrays more time ...
1k views

### NDSolve, Schrödinger equation, and decaying solution

I am trying to solve a Schrödinger equation for a particle hitting a step potential using NDSolve in Mathematica. Here is my code: ...
302 views

### Why can't NumberQ be used as the head of a pattern?

Consider the following: list={1/First[{}], 1, 2, 1/First[{}], 3}; DeleteCases[list,_NumberQ] I wanted to remove all cases, which did not match ...
949 views

### SIGSEGV error with 3D Plots

I originally asked this question here but didn't get a satisfactory answer. I am using Mathematica 8.0.1.0 on Ubuntu 11.10. I created a 3D plot from an ...
1k views

### Does every Symbol in Mathematica induce a monad?

From my question about types in Mathematica, I assume that every Symbol in Mathematica is a type if it appears as a Head of some ...
823 views

### Why does CUDAQ (from CUDALink) download data from Wolfram servers?

I understand why functions like ElementData or CountryData need to download up-to-date data when first launched. However, when ...
2k views

### What is a type in Wolfram Mathematica programming language?

"Everything is an expression" is a popular citation from many Mathematica guidebooks. So, what is type in Mathematica? How does it relate to common types from Haskell, for example? I did some ...
3k views

### Replacing composite variables by a single variable

To replace a single variable by another variable, one can simply use the the replace all (/.) operator (e.g., ...
656 views

### How do I generate the upper triangular indices from a list?

I have some list {1,2,3}. How do I generate nested pairs such that I get {{1,2},{1,3},{2,3}}? That is I'd like a way to ...
10k views

### Plotting Complex Quantity Functions

Trying to plot with complex quantities seems not to work properly in what I want to accomplish. I would like to know if there is a general rule/way of plotting when you have complex counterparts in ...
327 views

### How to “ignore” an element of Map or MapIndexed

Say I have some function that I'm applying every element in a list to... if that element matches some criteria: ...
1k views

### Splitting words into specific fragments

I am looking into splitting words into a succession of chemical elements symbols, where possible. For example: Titanic = Ti Ta Ni C (titanium, tantalum, nickel, carbon) A word may or may not be ...
714 views

### Adding a circle to an already existing drawing

With reference to my earlier post: Adding a point to an already existing graphic I would like to add an outer circle to the whole drawing. This outer circle is a fixed one of ...
1k views

### Number format of axes in a plot

How can I have a conditional format of the values appearing in the axis of a plot ? I have in mind the number format options available in Excel for plots as described here ...
8k views

### Formatting legend text font

I am using this code to plot a graph, and I am trying to make the font of the legend bigger. ...
316 views

### Using the same frame ticks for two different histograms

Consider the following: ...
2k views

### Google Map in Notebooks?

Using Mark McClure's GPXToGoogleMap results in a HTML and Javascript code which can be viewed by any browser. Is it possible to load this map into the notebook, which obviously means for example that ...
194 views

### Solve[ ] with Method -> Reduce gives a different result than Reduce[ ]

Why does Solve[Sqrt[x + Sqrt[x]] - Sqrt[x - Sqrt[x]] == m Sqrt[x/(x + Sqrt[x])], x, Reals, Method -> Reduce] give a different result than ...
863 views

### Reading from STDIN, or: how to pipe data into Mathematica

Today I tried using Mathematica's plotting capabilities to display the output of a C++ program. This made me wonder whether it is possible to somehow tell a Mathematica script to read from STDIN and ...
262 views

### Matrix multiplication involving MatrixForm [duplicate]

Possible Duplicate: Why does MatrixForm affect calculations? I am doing a matrix multiplication, but not getting the desired output. I am doing the matrix multiplication of $A^{-1}B$ from ...
216 views

### How do I write a ValueQ function that only returns True if there exists an OwnValue?

Reading the comments in this answer has motivated me to request a full solution to part of this problem. What I'd like is an efficient solution that returns True ...
360 views

### Conditional Gathering of lists

Just need a little help with the GatherBy / SplitBy function(s). I have a list of random numbers here: ...
4k views

### Importing from Excel

I'm trying to import a matrix from Excel to Mathematica. My code is: Import["desktop/stproj.xls", "xls", data, 1] The output is some weird stuff about population ...
286 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 ...
745 views

### Is there a convenient way to copy/paste text-interspersed SE code snippets into Mathematica?

Is there a way to copy and paste code snippets from SE to Mathematica if these snippets are interspersed with text? Like e.g. in Morphing Graphics, color and location in both the question and answer, ...
1k views

### Morphing Graphics, color and location

I would like to make a small animation : 1-We start with a random distribution of gray points : ...
360 views

### Arguments to If[] are not evaluated

I got bitten by the following: f[x_] := 3*x; g[x_] := If[Log[f[x]] < 0, f[x], 0]; g[x] Out[11]= If[Log[3 x] < 0, f[x], 0] where I thought the call to ...
2k views

### Fetching data from HTML source

I want to generate a couple of plots/graphs with Area51 statistics. Since Area51 doesn't work with the SE API, I'm forced to find another way to get the information I want. That other way is with ...
310 views

### Setting parts of a list

Suppose I have list a = Range[10] {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} in which I want to set some elements to be a list ...
533 views

### How to properly DumpSave & Get Global`s symbols inside packages while not touching Global context?

For efficiency reasons I prefer to use DumpSave instead of Save. For ease of access I prefer to save symbols in ...
264 views

### Old values are not freed/garbage collected when you re-evaluate an assignment

For this code: (* Cell 1 *) generate := Module[{x}, x = Range[100 * 1000 * 1000]; x]; (* Cell 2 *) g = generate[]; MemoryInUse[] If I evaluate cell 2 ...
785 views

### How to set the NDSolve method to LSODA

I notice that off all the Method options available for NDSolve[...], LSODA is invoked quite ...
270 views

### presenting a real number as real instead of imaginary

I have an equation which results in an answer of the form $\frac{i a}{\sqrt{c-d}}$ is there any way to get Mathematica to present it in it's real form? like $\frac{a}{\sqrt{d-c}}$ I know that I ...
644 views

### How to get string representation (like repr in Python)

I have a string variable. I want to obtain another string which contains the representation of the string variable content itself. s = "a \n b" I need to get a ...
I have two nested solid figure, where $V(a,h,\tau)$ defines the volume and $A(a,h,t)$ defines the surface. The outer solid figure is parametrized in $a_s$,$h_s$ and $t_s$ (they share a common center). ...