# All Questions

262 views

### How can I make the output from Solve look nice?

I have a problem with presenting solutions. Roots of 4th order polynomials are big expressions. Is there a way to present the roots, s2 and s3, in normal form with some substitutions? Maybe a way to ...
157 views

### writing a function using multiple variables

I am fairly new to Mathematica and am trying to write a function for the equation: xx = [x/(Sqrt[h^2 + d^2 + y^2]))*(Sqrt[h^2 + (d + yy)^2]) where h, d are known ...
2k views

### How to check if an expression is a real-valued number

What is a simple, fast way to test whether an expression is a real-valued number? I ask since there is no RealQ function. If we call this test ...
354 views

### Make contour lines level with graph interval?

I am graphing the voltage traveling through some water with two electrodes. I have the graph with contour lines and all, but is there any way that I can get the contour lines to be at the tick marks ...
453 views

### Packages problems on version 9 under OS X

Using Version 9 on OS X, I've run into some problems with creating packages and accessing them. I've done the following: wrote all the function definitions in a notebook and tested that they all ...
115 views

### How can I truncate only a single vertex of a polygon?

One can truncate all the vertices of a polygon at once with Truncate. I want to do exactly that -- but only on a single vertex. Is this possible with Mathematica 9? ...
112 views

### Parallel computing NInverseFourierTransForm

I am running the code below, and it works perfectly. I have some function in Fourier space, and I take the numerical InverseFourierTransform. However, I will have ...
614 views

### Mathematica Mac Keyboard Shortcuts not Working?

Really I'm just trying to use the Ctrl+2 shortcut to make a radical, but for some reason this won't work. What could possibly be going wrong? The exponent shortcut works (i.e. Ctrl+6).
214 views

### A Sierpinski-ish structure, via 2D automata

The project is originally based on a puzzle proposed by EIORU at http://www.ptt.cc/bbs/puzzle/M.1342451949.A.00F.html (若您懂得讀中文 / if anyone happen to read Chinese^^) last July. The descriptions, ...
904 views

### Monte Carlo simulation using geometric Brownian motion

I'm relatively new to Mathematica programming, so forgive my rather unsophisticated question: I'm trying to do a Monte Carlo simulation using geometric Brownian motion (GBM). I want to write a ...
516 views

### mathematica startup time

I have Mathematica 7 and 8 installed on my laptop. Mathematica 7 starts quite fast, but Mathematica 8 is extremely slow to start. In the Option Inspector I canceled the "welcome screen" option at ...
785 views

### Avoiding grid lines inside filled area in RegionPlot exported as PDF

Basically the same question as here, but now with regions which have opacity. ...
405 views

### Modeling neural excitation with a non-linear differential equation

I think I have a special problem and I am not sure how to search for an answer, so I thought I would try here. I am working with the so called FitzHugh-Nagumo model which describes very simple ...
460 views

### DataEncoding and compression in HDF5 format

I would like to export data in HDF5 format with Mathematica 9. The Mathematica manual about Import and Export of this format can be read here. As I'm dealing with large arrays, export often lead to ...
268 views

### Handling error in database connection (TimeConstrained)

I have a lot of scripts that use a database connection, and I have realized that my code should be protected against errors in my connection. For example, when my database is out for some technical ...
2k views

### How to use Graphics@Rotate@Show@Graphics without “Graphics is not a Graphics primitive or directive.”

If I have the following graphic: ...
124 views

### Syntax highlighting in patterns with built-in functions

While working on my own plotLegends package I encoutered some weird behaviour of the front end's syntax highlighting. I reduced the problem to the following minimal ...
296 views

### Frequency of elements in a list (merging tally data) [duplicate]

I've got a list in the format of list={{a,1},{a,1},{b,1},{c,1},{b,1}} And I want it to "compress" into a list of pairs ...
603 views

### Removing -> from list of numbers [duplicate]

Possible Duplicate: Best way to extract values from a list of rules? If I have a vector v = {x->1.03, x-> 2.01, .... }, and I want to use an element in the list, I can get an element as ...
8k views

### Finding unit tangent, normal, and binormal vectors for a given r(t)

For my Calc III class, I need to find $T(t), N(t)$, and $B(t)$ for $t=1, 2$, and $-1$, given $r(t)=\{t,t^2,t^3\}$. I've got Mathematica, but I've never used it before and I'm not sure how to coerce ...
252 views

### Creating Recursive Sequences

Quite a simple question, I reckon, however, even quite an extensive search hasn't helped me. I want to define a recursively defined sequence that starts with defined ...
229 views

### Finding parameters for first positive root of solution to differential equation to be equal to a desired value

I have a differential equation with parameters. The objective is to vary the parameters such that the first positive root of the solution is equal to a desired value ...
134 views

### Throwing away all expression on a loopback link

What is the simplest way to throw away all expressions waiting to be read on a loopback link, effectively resetting the link? I am building an expression on a loopback link using the C MathLink ...
176 views

### Feedback on my Subscript code

I have written a code, and I need a little feed back.. I want to make the Subscript distributive across (1) addition and (2) multiplication to mimic short-hand for ...
618 views

### Asymptotic expansion, negative powers

The question was inspired by this discussion: How to expand a function into a power series with negative powers? I am interested in asymptotic behavior of a function at infinity: ...
561 views

### Volumetric analysis from topological maps

I want to calculate the volume of fill required to level an area about the size of three foodball fields. The Department of Public Works in my city can provide me with topo data for the area. Their ...
266 views

### Is there a better way to get the eight points of intersection?

I want to get the eight points of intersection from the equations 2 Abs[x] + Abs[y] == 1 and Abs[x] + 2 Abs[y] == 1. To solve ...
333 views

### I can't get Compile to work

I've got some problems with my code, and I try to make it faster. Some of you suggested me to split my problem, and I'm here... I post the same function with and without Compile. This is a support ...
664 views

### Why doesn't FullSimplify get rid of the common factor in this expression?

FullSimplify does not get rid of the z factor in the following expression: ...
313 views

### Function that evaluates in notebook does not evaluate in CDF

I am trying to access the values of a dynamic value outside function package. Within the function package, the function is defined under the Dynamic module option. There is an error with this. I ...
250 views

### How can I eliminate equivalent equations from a list?

I want to find the numbers $a$, $b$, $c$, $d$ of the plane $ax + by +cz +d = 0$ which make the distance from the point $M(1,2,3)$ to the plane equal to 2. I tried ...
207 views

### Plot in cylindrical coordinates [duplicate]

I am trying to plot a simple vortex in cylindrical coordinates give by $v_{\phi} = \frac{\Gamma}{2 \pi r}$ Is there an alternative method to plot this than, for example, using streamplot and ...
823 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 ...
1k views

### Use Mathematica as a terminal

I love how notebooks work in Mathematica. You can edit code in real time and hit Ctrl+Shift to run it. Additionally you copy and paste different cells around to organize and test ideas. Search ...
4k views

### Summing along rows or columns of a matrix

I have a list of rows in database such as {{a,b,c}, {d,e,f},{g,h,i}} I want to be able to add each row across and each column down (like a spreadsheet). In other ...
459 views

### What's the analogue of UML in Mathematica land?

What's the analogue of Unified Modeling Language (UML) in Mathematica land? Mathematica has elements of object-orientation, but most Mathematica programs or applications aren't of object-oriented ...
888 views

### Plotting series solution to the heat equation [closed]

I am trying to plot a solution to the heat equation $u(x,t) = \sum_1^\infty \frac{8(-1)^(n+1)}{\pi^2 n^2} \sin(n \pi x) \exp(-n^2 \pi^2)$ I am using the following from another answer here on ...
799 views

### Built-in unit strings recognized by Quantity?

It’s great that Quantity can utilize Wolfram Alpha to interpret unit strings that it doesn’t recognize, but I need my code to work on machines that do not have Internet access. Is there a complete ...
211 views

### Why does $\frac{\partial}{\partial x}O\left(\left(\frac{1}{x}\right)^0\right)$ equal $O\left(\left(\frac{1}{x}\right)^0\right)$ in a series expansion?

When taking the derivative of a series expansion around a finite point, the $O(x^n)$ part is differentiated as expected. $O(x^n)$ becomes $O(x^{n-1})$ except $O(x^0)$ which stays $O(x^0)$. When ...
399 views

### how to work with list as function parameter

I want to output an arrow based on input from user and I tried writing this small function to achieve this: ...
447 views

### Is there a Break[] equivalent for short-circuiting in Table?

I am running Mathematica 7. The following is admittedly a silly example, but suppose that I have a list list whose entries are either ...
2k views

### NSolve: Mathematica 9 issue

In Mathematica 8 the following expression evaluates and returns a result in terms of InverseFunction: ...
1k views

### Finding face vertices from the face adjacency graph

I have a question about face adjacency graphs. Suppose that I have an adjacency matrix ...
252 views

### Since installing mathematica 9 I can't import certain tiffs

I have a notebook written in Mathematica 8 in which I imported Tiff images and everything worked fine. Since I installed Mathematica 9, I get the error: ...
617 views

### How can I create a fountain effect?

Inspired by this (please use Chrome or Firefox), I tried to simulate it, but I couldn't do it. I'm not familiar with Dynamic. Here is my simple code: ...
298 views

My code: ...
493 views

### More than one expression in the Table[] command?

I would like to construct a Matrix using the Table[] command. The issue is that I would like to use more than one expression for it. What I need to obtain is something like this : ...
2k views

### How to convert a hex color string to RGBColor?

For example: "#FF8000". How could I convert it to RGBColor or Hue?