1
vote
2answers
90 views

Missing something in my input for CountryData dependencies

I'm trying to find (a)which countries have dependencies (b)and a list of countries that consider themselves dependencies (c)and a list of countries that don't consider themselves dependencies. ...
-1
votes
1answer
396 views

Gamma Incomplete Function representation in Mathematica and Matlab

I am confused about Gamma Incomplete function calculation in Mathematica and MatLab: For example, in Mathematica: Gamma[5,3] = 19.56 But in MatLab: ...
8
votes
2answers
270 views

Problem importing a JCAMP-DX mass spectral file

I have some problems importing a JCAMP-DX EI-mass spectral file using Mathematica 9. For example, if I download the mass spectrum of nonacosane in JCAMP format from NIST, ...
0
votes
1answer
131 views

Manipulating and using result of DSolve

I have an unsightly looking equation that nonetheless has an analytical solution. The solution is ugly as hell, but exists; I use the following code with the DSolve ...
4
votes
2answers
861 views

ArcTan[z] and ArcTan[x,y], Restriction and Conversion

In Mathematica there are two different forms for the arctangent (inverse tangent), namely ArcTan[x,y] which gives the arc tangent of $y/x$, taking into account ...
2
votes
1answer
229 views

Why is this expression being held, and how can I evaluate it?

I can't figure out why an expression isn't evaluating, even though there's no Hold* in its FullForm: ...
2
votes
4answers
202 views

Where did I go wrong with my implementation of finding a plane tangent to a surface?

I am working on finding the plane tangent to a paraboloid at a given point. My code: ...
1
vote
1answer
163 views

DSolve expression not evaluating

I entered the following into Mathematica: p[x_] := 4 x q[x_] := 4 Sqrt[x] - 3 f[x_] := E^-Sqrt[x] DSolve[y''[x] + p[x] y'[x] + q[x] y[x] == f[x], y[x], x] ...
3
votes
1answer
203 views

When does the real part of Zeta vanish on the critical line?

This seems to be a quite a simple problem but I cannot make it work. I am trying to find all values within a given range for which the real part of the Zeta function vanishes on the line: ...
1
vote
1answer
322 views

How to effectively compare two sentences and say both are equal

want to compare two text file. Suppose file AA contains following text ...
6
votes
1answer
269 views

Efficiently searching a list for the position of the closest number to a specified number

Searching by closest and position I wasn't able to find an answer—but found Nearest by guessing. Nearest, however, returns ...
1
vote
3answers
150 views

automatic processing of numerical results in `Plot`

First I want to solve an equation $F(x,y)=0$ for $y$ by supplying a value of $x$. (suppose obtaining the analytic form of $y(x)$ is too difficult) Then I want to plot root $y$ (numerically calculated) ...
1
vote
1answer
149 views

Plot3D missing a zone

I am trying to plot a simple graph using Plot3D: ...
3
votes
2answers
295 views

Assigning an analytical approximation to the error function erf(x)

Working with some iterative integral equations I have Gaussian density functions involved therein. Integrating the gaussian function I obrain the error function. When I take the second integration, ...
0
votes
1answer
104 views

Function generating a rule with a Patterns: e.g. toRule[ lhs, rhs] into lhs[x_] -> rhs [duplicate]

I want to create a rule as a function of z from a left and right hand side. My (non-working) code and usage is: ...
0
votes
2answers
86 views

Display Part Of or Summarize Other Notebooks

How might I display parts of(or basically summarizing) one Notebook from parts of several other Notebooks? This isn't a strict question question but more of a general/wiki question of how to organize ...
3
votes
3answers
317 views

How Can I superpose an image and a graphics?

I want to superpose an image with a graphics in order to evaluate their alignment. I am writting this exemple of code. ...
1
vote
1answer
619 views

Is LinearSolve the most robust way to solve the equation $Ax=b$?

I want to solve the equation $Ax=b$, where $A$ is an $n\times n$ matrix, and $x$ and $b$ are $n\times 1$ column vectors. Here $n=124$. LinearSolve[A,b] I got the ...
0
votes
2answers
260 views

using index notation for finite differences

I am interested in deriving finite difference equations, which means I have to play around with indexed quantities. For example, for a 2D function f(x,y), I could discretize it on a grid with grid ...
1
vote
1answer
134 views

Problems with formatting a bar chart

I am trying to create a financial dashboard using Mathematica. I am having trouble formatting the axes ticks to show whole numbers. Further, when I hover over one of the chart elements, it is ...
1
vote
1answer
220 views

No Speedup Compiled Function in FindMinimum

The problem: I would like to minimize an objective function with respect to 12 variables. Minimization should be executed as fast as possible. Compiling the objective function increases the execution ...
5
votes
0answers
135 views

Texture[] not working properly with Image AlphaChannel

I recently encountered a problem when combining multiple texture layers in an graphics object when the texture comes from an image with alpha channel. Apparently the alpha channel of the image passed ...
1
vote
0answers
33 views

Pattern matching list elements in pure functions [duplicate]

Pattern matching here is a functional programming term, but it might be called differently in Mathematica, I'm not sure. It is possible to match the elements of the list in a regular function ...
0
votes
1answer
179 views

Plot lines keep disappearing

I'm trying to plot the Compton Shift which I've defined as: E2[ϕ_] := E1/(1 + (E1/(m*c^2))*(1 - Cos[ϕ Degree])) I've initiated the constants and when I evaluate ...
4
votes
4answers
263 views

How to compute MIN$(A(x), B(x))$

I have two polynomials: $\;A(x) = \sum a_i\;x^i$, $\quad B(x) = \sum b_i\;x^i$. Given $A(x)$, $B(x)$, I want to compute $\;C(x) = $MIN$(A(x), B(x)) = c_i\;x^i$ where $c_i = $MIN$(a_i, b_i)$. How can ...
7
votes
1answer
444 views
0
votes
0answers
172 views

Connection between Mathematica Connector/J and XAMPP MySQL Database

I have been fiddling around with a problem for a while now, and hope you can help me. Have searched for previous solutions, but nothing seems to work. My problem is as follows: I have XAMPP ...
8
votes
5answers
282 views

Refer to next element of list when iterating using Map [duplicate]

Is it possible to refer to the next element of the list when I'm using Map or should I always use For in this case? For example ...
1
vote
1answer
398 views

FindMinimum [] methods

Which algorithm is used when we do not use the option Method of FindMinimum[] function. FindMinimum[f,{x,x0}]
1
vote
0answers
101 views
12
votes
1answer
315 views

Is everything in Mathematica ultimately stored as a rule?

My current understanding about Mathematica is that everything, at the lowest level, ends up as replacement rules. First question: is this true? Second question: does Mathematica "gloss over" these ...
1
vote
1answer
120 views

What's wrong with my palindrome finding function?

I'm trying to find the palindromes in the dictionary, but my output isn't giving me all of them. I have this so far ...
0
votes
0answers
25 views

DialogInput inside ButtonBar freezes Mathematica [duplicate]

In Mathematica 8, if I press a button on a ButtonBar which contains a DialogInput Mathematica freezes. Is this reproducible and ...
2
votes
1answer
518 views

Differential equations: Solving a singular/nonlinear ODE using NDSolve

I am trying to numerically solve a rather horrible looking singular/nonlinear ode: A*(y''[x]/y[x])'' +y[x]^2==1 on the interval ...
0
votes
0answers
102 views

calling a batch or executable application on Windows

How to run a batch file, send commands and collects output on windows Run["!C:\\runme.bat"] it outputs 1 and a window appears and then disappears. I also want ...
0
votes
1answer
215 views

Customizing AxesStyle->Arrowheads

How do I call AxesStyle->Arrowheads[ ] in order to control whether or not an arrow appears on each of the four ends of the axes in a ...
2
votes
1answer
85 views

File output and race conditions

Is it possible to know when Mathematica is done writing a file? I'm looking to automate something and I'm wanting to have Mathematica put it in a file using Put[], ...
2
votes
2answers
187 views

How to replace data in a list (tree) in a functional Mathematica way?

I have list containing 2D points in various groupings, i.e. points, lists of points (figures), lists of lists of points (patterns) and finally a list of patterns. The list also contains other data, ...
0
votes
1answer
314 views

Convert expression to C-form and simplifying

I have an expression which is the sum of many terms of the form $$ \frac{0.00000000274341}{(0.000363856+(0.611425+z)^2)^{3/2}} $$ My problem is that I need to include this long expression in a ...
6
votes
1answer
172 views

Random filling of L-length line with l-length segments

I have discrete L-length line filled randomly with 2-length segments so its cover line with gaps 0 or 1. So we can describe cover configuration as sequence of gaps such as {0,0,1,0,1}. How I can ...
5
votes
2answers
154 views

Strange Behavior when making Equal Listable in Pick

While trying to make this problem more efficient I tried different methods and dabbled with making Greater and Equal ...
4
votes
3answers
606 views

How to increase Spectrogram resolution?

I have a time-domain signal that I want do a time-frequency analysis on it. When I tried the Spectrogram, I always get very low resolution. For example: I have a ...
2
votes
1answer
297 views

How to use NIntegrate in a purely numerical mode?

I have a function that is defined as the smallest root of a given polynomial. Something like this: ...
4
votes
2answers
207 views

J/Link: How to run a thread inside Mathematica

In the J/Link User Guide there is no example on how to use java.lang.Thread, from inside Mathematica. I'd like to know if is possible to start a thread from a ...
6
votes
1answer
89 views

Why only up to two \[Prime] superscripts are interpreted as derivatives?

I noticed that only up to two \[Prime] superscripts are interpreted as derivatives. Is there a reason for this restriction? Is it documented? ...
3
votes
1answer
160 views

Adding and summing overlapping Airy (or Gaussian) disks on a plane

In a previous question of mine, I asked how one might draw an Airy disk on a plane: Generating an Airy disk on a plane, and recieved some impressive answers from the users Timothy Wofford and ...
3
votes
0answers
126 views

What is the signature for a callback function for FinancialIndicators?

I'd like to write my own indicators to use with functions like TradingChart. From the context, it's clear that one needs to write a function whose parameters ...
2
votes
1answer
160 views

Copying each object in a plot separately as an image

I would like to copy a plot from Mathematica as an image, into a PowerPoint slide. This plot has two curves. When I try to do the (naïve) usual "copy graphics" and paste, I find the full plot (along ...
0
votes
2answers
140 views

Put results in multiple columns for comparison

One thing I would like to do in many instances is arrange input/output in columns for comparison. I expect that I need to use Grid to do this, but have not been ...
6
votes
3answers
280 views

Where did I go wrong with my implementation of the trapezoidal rule?

One method for doing quadrature, called the trapezoidal rule, improves accuracy by connecting the points on the curve corresponding to the points of subdivision with line segments, forming trapezoidal ...

15 30 50 per page