# All Questions

750 views

### Solve a PDE on a domain $\Omega$ with given boundary conditions

I'm starting to study the behavior of some PDEs and I would like to run simulations in mathematica to help me visualize solutions. For example, a prime example that I would like to study is  ...
117 views

### Esc-esc for special characters and autocomplete in Mathematica 9 [duplicate]

I recently upgraded to Mathematica 9 and have noticed a slightly annoying behavior that I was looking to remedy. In the past I would type special characters, e.g. ...
728 views

### Plotting multiple lists of complex numbers

The user #Nasser showed an elegant way to plot complex numbers: ...
379 views

### What is the fastest way to replace all zeros in a matrix?

In the following matrix m every 0 should be replaced with a 1: m = {{0,1,2},{5,0,3},{8,0,0}} Desired result: ...
563 views

### How to I display the value of my plot function?

I've plotted a function that varies with respect to time. It's inside a manipulate box, which can vary the time. And I'd like to display the value of the function at the time on the slider on my plot. ...
3k views

### How can I plot implicit equations?

If you enter the following into Wolfram | Alpha, you get nice graphs: graph 4 x^4 + y^2 = 2 How do you do this in Mathmatica? I realize that these are not ...
412 views

### Import an SPSS, SAS, or STATA file into Mathematica

I would like to import the World Value Survey data file into Mathematica, but it's only given in spss, sas or stata formats, which are statistical analysis softwares format I think. I can't get to ...
529 views

### NIntegrate & non-numerical values

I am wondering why I am receiving the message "The integrand ... has evaluated to non-numerical values for all sampling points in the region ..." for a particular calculation I am running. How can I ...
187 views

### How can I mix colors?

As far as I know if you combine Blue and Green the result is Cyan (using additive mixing). ...
273 views

### Random Matrix with integer coefficients and inverse also having integer coefficients

I'm trying to build a function that gives me matrices such that each: Has integer coefficients. Is non singular. Has inverse which also has integer coefficients. I have some code that one of my ...
241 views

### Visualizing nested lists for easier human understanding

When interacting with Mathematica, I often find myself staring blankly at waves of curly braces, trying to understand how data is organized hierarchically. For example, the beginning of the result to ...
508 views

### Simulated Annealing InitialPoints option

I have a cost function that depends on 4 parameters: CostFunction[{tx,ty,tz,ox}]. I used NMinimize[] function with ...
234 views

### Solve[polynomial, x, Reals] doesn't get all real roots or correct ones?

My main confusion is about the difference between the two code blocks at the end of this long spiel, but the spiel contains the code to create the polynomial if its coefficients are helpful for ...
103 views

### NMinimize memory consumption problem in Mathematica 9 vs. 7 & 8

I am having trouble using NMinimize in Mathematica 9 - Memory consumption overflows. The same NMinimize command, with the same ...
219 views

### plotting an Integration output

How to solve this integral by Mathematica even by numerical methods (plotting the solution) Integrate[(Cos[x] - a)/(1 + a^2 - 2*a*Cos[x])^1.5, {x, 0, 2*Pi}] It ...
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. ...
400 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: ...
273 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, ...
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 ...
872 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 ...
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: ...
203 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: ...
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] ...
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: ...
331 views

### How to effectively compare two sentences and say both are equal

want to compare two text file. Suppose file AA contains following text ...
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 ...
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) ...
149 views

### Plot3D missing a zone

I am trying to plot a simple graph using Plot3D: ...
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, ...
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: ...
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 ...
320 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. ...
628 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 ...
266 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 ...
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 ...
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 ...
136 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 ...
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 ...
181 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 ...
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 ...
448 views

### NIntegrate receiving a function with NumericQ which returns a list

Can some one please explain why ...
173 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 ...
283 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 ...
404 views

### FindMinimum [] methods

Which algorithm is used when we do not use the option Method of FindMinimum[] function. FindMinimum[f,{x,x0}]
101 views

### ContourPlot of implicit function doesn't work when I square the equation [duplicate]

When I try this ...
316 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 ...
122 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 ...
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 ...