# All Questions

16 views

### How to simplify a differential equation?

Now I get a differential equation like this: (-1 + x) (1 + x)^2 == (2 (1 + x^2) (1 + x^4))/(-2 x (1 + x + x F[x]) + (-1 + x^3) F'[x]) I want to get the standard ...
5 views

### Faking MoleculePlot for compounds where it isn't available

Mathematica's ChemicalData has a lot of useful information, but many compounds only have flat 2D structure diagrams rather than the cool 3D ...
12 views

### How to apply pattern like Alternatives in EuclideanDistance command?

we have a list of list of points coordinate, ...
19 views

### Mathematica Integration Problem

I am new user of Mathematica. Can anybody help me to solve this integration? I really needs your help. Integrate[(1 - (1/(1 + A x^(-ao)))) x, {x, 0, r}] Can ...
13 views

### How can I bypass the limitations of init.m?

In a series of QA it has been pointed out that init.m suffers of heavy limitations (see as example, Automatically load packages at startup or Why can't I import ...
11 views

...
43 views

### Get the coefficient matrix from a quadratic form

Suppose I have a quadratic form of qf = a x^2 + b y^2 + c z^2 + 2 d x y + 2 e x z + 2 f y z How can I easily to get the symmetric matrix A, such that ...
83 views

### Implicitly inverting a function from numerical solution

I have the following piecewise continuous function: ...
15 views

### Change position of data labels in BarChart3D

What would be the easiest way to manipulate the position of the chart labels in "Grid" layout in a BarChart3D? For example: ...
31 views

### Replace every power of $e^{i\theta}$ with $z$ [on hold]

If I have the expression $\frac{1}{13-\frac{5}{2} i \left(e^{-i \theta }-e^{i \theta }\right)}$ and I want to replace each $e^{i\theta}$ with $z$, so that the result is ...
44 views

### How to find a root for an integral equation?

I try to find numerical solution $E_f$ to satisfy the following equation: ...
82 views

### Syntax f[x_][y_]

Need to understand the principe of the distinction between f[x_,y_] and f[x_][y_] It seems also that ...
107 views

### Evaluating standard functions of general quaternions symbolically

Mathematica can easily compute exponentials and logarithms of concrete quaternions: ...
64 views

### Finding roots of Bessel function $y=3J_1(x)+xJ_1'(x)$ is returning inaccurate roots. Not Kernel bug [on hold]

I can't figure out why Mathematica is returning the incorrect roots. The first five should be 2.9496,5.84113,8.87273,11,9561, and 15.0624 according to my textbook. ...
63 views

### Root of a cubic is not always real [on hold]

In my Mathematica output, the following root object occurs ...
83 views

### Is it better to completely forget about the existence of PowersRepresentations?

I noticed that in several cases the performance of PowersRepresentations is hugely worse than that of IntegerPartitions. (Mma ...
168 views

### Is it possible to get the (x, y) position of nodes in a Graph?

Given a graph... RandomGraph[{20,40}] ...is it possible to retrieve the (x, y) coordinates at which the nodes are drawn? ...
29 views

### Plotting function described by other functions!

I want to plot and manipulate my VS function which comes from the other functions above it. So, what should I use in order to draw my function considering that it is described by other functions. I ...
219 views

### Deriving a PDF for an annulus distribution

I would like to derive the PDF for an ''annulus'' type distribution, defined by the parameters $\theta\sim U(0,2 \pi)$ and $d\sim N(0,\sigma)$; where $\theta$ is the angle round a circle of radius ...
41 views

### Bug in Mathematica 9 (Quaternion)

The code: << Quaternions`; Exp[Quaternion[1, 0, 0, 0]] produces an error: ...
118 views

### Integrate producing bad result

I noticed a bug in Mathematica. It computes incorrectly a definite integral ...
33 views

### A function for replacment in mathematica [closed]

when you have too many replacements such as a1 x+ b2y + c1 z/.{a1->s^2+b^2,b1->r^2+g^2,c1->f^2+k^2} is it possible to define a vector like this ...
59 views

### How to find intersection points of linear and semi-logarithmic plots

Hopefully the title depicts what I am trying to do. Below is a figure of my calculations that is shown in logarithmic scale in the x-axis. I am trying to find a way to find the intersection point at ...
41 views

### A question on JordanDecomposition in Mathematica

How can I have Mathematica show me also the inverse matrix of the similarity matrix of JordanDecomposition of a matrix? Obviously I need to use here the ...
53 views

I am trying to install the FeynCalc package, but I cannot load it, it always gives the following errors: Loading FeynCalc from /home/gabi/.Mathematica/Applications SetDirectory::cdir: Cannot set ...
58 views

### expressing a rising factorial as a polynomial

I have an equation in $x$ as follows: $f(x)=\prod_{j=0}^{k}(j+x)=x.(1+x).(2+x)\cdots.(k+x)$ I want to express this as a polynomial in $x$, i.e., as $a_0x^0+a_1x^1+\cdots+a_kx^k$ I tried doing the ...
136 views

### Replace For with If in Mathematica way

I have this code: ...
127 views

### Why FoldList 5 times faster than Apply for matrix multiplication?

Consider this list of $2\times 2$ matrices: list=RandomReal[{-2,2},{500,2,2}]; Now compare timings of Apply and ...
44 views

### What is it with MemberQ? [closed]

Look at this operation MemberQ[x^3, x^3] (* False *) Is it correct, or a bug?
275 views

### How to measure the slit size from given image using mathematica?

I want to measure the size of the optical slit from the microscope image. Here is the image. The dimension of image data is {1300,1030} and the real pixel size is 6.7 micron. But the problem is ...
301 views

### upper envelope of data

Here is a ListPlot[] of some data. Clearly, there is a fairly smooth upper envelope - the question is whether there is an nice way of extracting it...
37 views

### NDSolve with coupled ODE's and unknown singularities

I have two coupled ODEs that I am trying to solve numerically. It appears that there is a singularity in the solution to the equations which I am unsure how to get past. Both functions $\alpha$ and ...
28 views

### Check if interpolated function passes through a specified region

Is there an efficient way to check if a curve that was obtained as an Interpolating Function (from solving differential equations numerically) passes through a given region? I am solving for two ...
52 views

### Pareto optimal fronts using internal function?

Reading this question: How do I estimate the Pareto front in my multiobjective optimization problem? I found @Daniel Lichtbau's interesting answer. Yet I don't know how such an "internal function" ...
48 views

### How to make Mathematica solve an equation in an analytic class?

Here is my small code: ...
43 views

### Solving a big number of non linear equations

I have three trapezoids. The first sharing its upper side (I will call b_{i+1} in the code) with the second, the third sharing its lower side with the upper side of the second. All shared sides are ...
12 views

### Palette Sizing Options

I am writing a palette to work with units on Mathematica 9, using just PasteButtons, and have a Button map that works as I want it to, but the formatting of the palette itself is giving me issues. I ...
58 views

### ListPlot with colors

Let's create some sample data n = 100; d00 = Table[{RandomReal[{-1, 1}], RandomReal[{-4, 4}], RandomReal[{-1, 1}]}, {i, 1, n}]; Now I want the following: create ...
49 views

### Trying to create a model and manipulate plot

I have been trying to learn mathematica to implement financial models in it. However, I am still very inexperienced in this :) Currently, I have what is presented below but I can't figure out why it ...
144 views

### solving coupled differential equations with parameters subject to optimization problem

I have an equation, but I don’t know how to program it in Mathematica: x[0]==1; y[0]==1; x'[t]==(a+b) x[t] y[t]; y'[t]==a b y[t]/x[t]; where ...
60 views

### Solve transfer function with non-zero initial conditions

Hand computation I have a transfer function defined as $\frac{0.6p+1}{0.6p^2+2.2p+8}$ which was derived from a circuit. Solving this by hand gives the equation, $$i(t)=Ce^{-1.83t}\cos(3.16t + \phi)$$ ...
28 views

### How to speed up Solve command in Mathematica 8.0?

I have two complicated mathematical functions $f(s)$ and $g(M)$ that are complicated functions of $s$ and $M$ respectively. I would like to solve the equation $f(s)=g(M)$ in order to plot $s$ vs. $M$. ...
32 views

### ColorBars or PlotLegends for ElementMeshSurfacePlot3D

I want to produce a colorbar legend to the output from ElementMeshSurfacePlot3D (Mathematica 10). The pde was solved using NDSolveValue (FEM pdesolution is the resulting interpolating function) over a ...
59 views

### Distinguish hashtag # operator when using multiple functions

I would like to do this list = Append[list[[#]],Map[list2[[1, #]] & , list[[#, 4]], {2}]] & /@ Range[Length[list]]; But I would like to substitute ...
56 views

### Integral invoving product of Whittaker functions

I'm trying to evaluate the integral $$\int W_{0,a}(x)\,W_{1,b}(x)\,\frac{dx}{x},$$ where $W$ denotes the Whittaker $W$ function, and $a,b\in[0,1/2]$. Using the Whittaker differential equations that ...
425 views

### webMathematica interface for Mobile apps

I was reading about webmathematica but it has mentioned that it is for websites and mobile apps depend on wolfram alpha to get its work done. But since exact mathematica code doesn't work in alpha, it ...
574 views

### Difference between = and Ctrl + =

What is a difference between $\textbf{=}$, and Ctrl + $\textbf{=}$? For instance there are some examples, but result is same. and
252 views

### How to construct a tree from a notebook?

Given the notebook itself we can think of it as a tree graph: the root vertex is the empty notebook itself, the headers of cell groups are vertices, and all other cells as leaf vertices. I'd like to ...
30 views

### Export list entries under a certain condition without using loops

I have a big list that contains many 3D- chains (set of points) and for each of them a polynomial. So the structure of my list is for example ...
72 views

### Rudimentary/basic simplifications of expressions not carried out--very puzzling!

Here's the raw input cell form--trying to follow MarcoB's suggestion--of the "offending" expression "g2": g2 = Piecewise[ {{(1/(1435*ra))(2(-1 + ra)^6*(11*ra^3*(-896*(201 + 16*rb) + .10*(368699 ...

15 30 50 per page