# All Questions

174 views

### Smooth out contour in RegionPlot/ContourPlot

I would like to smooth out the jagged edges in the outermost contours in the following plot: I have data of values as a function of variables (x,y) in the form ...
399 views

### Exponential of a Differential Operator

In Mathematica, is it possible to exponentiate a differential operator such that the operator will act on a function, $f(x,p)$? Specifically, I wondering if I can get Mathematica to do this: ...
1k views

### A question regarding 1 divided 243

Here is a problem due to Feynman. If you take 1 divided by 243 you get 0.004115226337 .... It goes a little cockeyed after 559 when you're carrying out the decimal expansion, but it soon straightens ...
111 views

### Laplacian in D Dimensions

Is it possible to compute $\Delta F=\nabla^2 F$ for $F=F(x^1,x^2,…,x^D)$ with $D$ finite? I seem to be only able to specify spherical coorindates, for example, if I want to leave standard ...
108 views

### Drop row if sum of part of row is equal to zero

My problem is the following: Suppose I have a matrix A which looks the following: ...
90 views

### How to force Manipulate to use preserve control settings over successive evaluations

I have this Manipulate: Manipulate[Plot[Sin[a x], {x, 0, 2 Pi}], {a, 0, 3}] Now, I realize I had mistyped the expression and it's actually ...
2k views

### Fitting points to tilted, off-center ellipse

I have 24 x-y points that are supposed to form an ellipse. ...
322 views

### Rotation matrix $\to$ quaternion

I found a very good link about quaternions in Mathematica , but I don't know how to create a quaternion from a rotation matrix. Can anyone help me, please? Update I need this: A rotation may be ...
88 views

### Strange numerical integration result

I write a function called berrycur[kx,ky] which I will give at the end of the question, and want to numerically integrate this function over {kx, -2π, 2π]}, {ky, 0, ...
128 views

### github api v3 repository create

I'm trying to create a github repository form a notebook, using this simple code ...
70 views

### Any command for group products?

Is there any Mathematica command or well known technique to take the direct product between two symmetric/permutation groups?
125 views

### I cannot get tables names and columns names from database

I am working with database using OpenSQLConnection-JDBC. I am able to fetch the data perfectly from the tables but I cannot get nor the names of the tables (using SQLTableNames) neither the column ...
168 views

### Error message: Coordinate index 0 is out of range for the enclosing GraphicsComplex

I am unable understand following error message: Coordinate index 0 is out of range for the enclosing GraphicsComplex. How to fix it? Attached data here: pts and polygons. See also end of question. ...
2k views

### How can I add a column into a existing Dataset?

I'm very excited about the brand new Dataset function. I have played with it in Wolfram Cloud, and haven't figured out how can I add a new column into an existing ...
204 views

### Alternatives ordering affects pattern matching in Cases?

Given expr = f[x, g[y], z] In the following query, the pattern h_[__, c_] appears as last slot in ...
352 views

### Trying to model Heat flow trough different materials with NDsolve

What I'm trying to achieve is model of the heat flow, in this case for the simplest 1D case,its relatively easy to do for the steady state case, but when I try to do it with NDsolve so I get the ...
54 views

### How do I constrain the result of fitting my non-linear model to be greater then 0

fitresulty21 = NonlinearModelFit[ydata21, {funfit[y, σ, A, B, x1, d, d/2], A > 0}, {{x1, 20}, {σ, 3}, {A, 200}, {B, 2000}, {d, 110}}, y]; ...
150 views

### Solve works with numbers but not number stored in variable

I have the code: ...
205 views

### Symbolic evaluation of the sum of KroneckerDelta

I want to evaluate this simple expression $$\sum_n f(n)\delta_{mn} = f(m)$$ using this: Sum[KroneckerDelta[m, n] f[n], {n, Infinity}] However Mathematica ...
526 views

### How do I save/export a list so that it can later be easily imported as a list again?

I have a couple of big lists (each of them contains elements that are themselves lists of two elements, i.e. an element of each list that I have is of the form {x, y}) that I want to save/export. ...
145 views

### Adjusting the vertices positions of a RandomGraph

By adopting the codes I got from the previous questions, here I intend to adjust the vertices positions of a RandomGraph. However, I only got an inactive graph, it even disappears suddenly when ...
109 views

### How do I estimate the Pareto front in my multiobjective optimization problem?

I need to minimize a function of two parameters that gives two "stress" outputs {A,B} = f[tau,mu]. How do I estimate (even roughly), the Pareto front for this ...
51 views

### using 'steps' in Manipulate

I want to make a 3D shape move through a specified graph; e.g. y = Sin[x], such that it moves up and down. My working so far has ...
60 views

### Solve[ ] for 2 variables not returning list of two variables

I type into mathematica: Solve[2 Sin[(Sqrt[3] x - 3 y)/2] == 2 Sin[(Sqrt[3] x + 3 y)/2], {x, y}] expecting it to return a list of pairs of solutions of the form ...
75 views

### Why does this integral have a complex result

I wanted to find the normalization of distribution F2 . ...
46 views

I want to set work for my 17 year old calculus students and have access to Mathematica 7. I aim to create a worksheet with rational expressions which they will then decompose into partial fractions. ...
147 views

### How to obtain all the distinct De Bruijn sequences?

In combinatorial mathematics, a $k$-ary De Bruijn sequence $B(k, n)$ of order $n$ is a cyclic sequence of a given alphabet $A$ with size $k$ for which every possible subsequence of length $n$ in $A$ ...
431 views

### How to export 3D graphics to Collada (.dae) format?

I'm looking for a way to export 3D graphics objects to the Collada (.dae) format. I need an automated way, i.e. using Blender to manually convert from another ...
42 views

### Comparing NIntegrate with definite integration

I want to calculate without error a sum of double integrals with the following definitions for the functions within them: ...
150 views

### Collect terms in a sum

Suppose I have this expression ...
106 views

### Cannot solve equation

I just started using mathematica and I'm facing a problem that I just can't solve. I want to solve the following equation: Code: ...
86 views

### Edit plot after creation [duplicate]

I try to find a way to manipulate a plot I created before. (for full code take the fuction x[t_]:=Sin[2t] ) Let's say I have a plot: ...
472 views

### Insert all elements from one matrix into another

I have two matrices $A$ and $B$ which are the same size. Each element of $A$ is a list of numbers. Each element of $B$ is just a number. How do I insert each element of $B$ into the corresponding list ...
67 views

### Alternatives to indexed variables in Compile

According to the excellent answer given here by @Leonid Shifrin: How to compile effectively?, You can not really use indexed variables in Compile, although it ...
111 views

### Assign values to variable names in lists

I hope somebody can help me in this (I guess) simple question: I have a list of variable names ls={w0,w1,w2} and another list of values ...
135 views

### Identifying the symbol which has a specific value

I'm writing a program that will solve the value of 1 variable in a 4-variable equality equation, but the variable to be solved will depend on the user's input to the program. This is what I've come ...
2k views

### Find intersection of pairs of straight lines

I have a list of 24 points, in which two consecutive points (1st and 2nd, 3rd and 4th, …) are supposed to form a line: ...
141 views

### How to power-series expand determinants?

Say $g$ is a matrix which is given as, $g = g_0 + xg_2 + x^2 g_4 .. +x^{d/2 -1}g_{d-2}+ x^{d/2}(g_d + h_d(log (x)))$ where $d$ is an even number and each $g_i$ is a matrix (same dimension as $g$) and ...
95 views

### How do I sum up p items in a sequence?

I have the following sequence list = {p1, p2, p3, p4 ....} I am summing up the p items as follows: p1 + p2 + 2*sqrt (p21*p2) = p12 p12 + p3 + 2*sqrt (p12*p3) = p123 p123 + p4 + 2*sqrt (p123*p4) = ...
188 views

### How can we ensure the result of Mathematica is exactly correct?

This is an example, I plot a function and find it has a defect when x approximates 400. Plot[Cos[.3 x] Exp[-0.01 x], {x, 0, 1000}, PlotRange -> All] Another ...
400 views

### How does Mathematica interpret a expression?

I'm a beginner to Mathematica. I'd read several document. But I still have a problem. For example, every expression in Mathematica are of the form ...
103 views

### How can I define a function that takes a list of reals?

I'm trying to define a function f which takes a list of reals. My purpose is to build a function which I can give a list of reals, integers or strings and have it ...
96 views

### Matrix operations performed with column-vectors

We have 3 matrices: m1, m2 and b. We want to apply matrix operations (dot or sum) in a ...
273 views

### How can I create a class of matrices programmatically?

I am trying to figure out how to create a function that can create the matrix pattern below, where: f[1] returns {{1}} ...
2k views

### What is the relationship between Mathematica and Wolfram Desktop?

I'm confused about the differences among various Wolfram products. In particular what is the relationship among Mathematica, Mathematica Online, Wolfram Programming Cloud, and Wolfram Desktop? Are ...
153 views

### Why the Mouse dragging response not as smooth as Locator

I am experimenting to use MouseDragged eventhandler to change the vertices positions of a triangle, it works, but not as smooth as using Locators. Is this the ...
459 views

### Export high resolution figure causes missing ticks

I understand that Mathematica has a bug when exporting images. The ticks are scaled not correctly when exporting at high resolution. For example: when you do: ...
123 views

### Using FortranForm

I need to use in Fortran, matrices that I create in Mathematica, therefore, I need to format them, so that Fortan can understand them. I focus on the simplest example: Let's say I have tha matrix A ...