# All Questions

59,249 questions
48 views

### Part::pkspec1: The expression j cannot be used as a part specification

I want to do some stuff with symbolic arrays like this a[[j]] + a[[j + 1]] == a[[j - 1]] + a[[j - 2]] But upon declaring such an expression I get ...
41 views

### Can a logarithm function with two variable be expressed as a Meijer-G function? [migrated]

Let {x},{y}>0 and {a},{b}>0. can the function log(1+ax+by) be expressed as a Meijer-G function?
57 views

### How to extract the data points in tabular form from a 3D region plot

I want to solve an inequality e.g. RegionPlot3D[x^2 + y^2 + z^2 > 300, {x, 2, 9}, {y, 3, 10}, {z, 4, 12}] and store x, y, z...
34 views

### What is causing this error in the Interpolation function?

I am using trying to understand someone else's code in Mathematica for the Finite Difference Method, except I changed a few values, but none of the code itself. Everything except for the Interpolation ...
25 views

### Why is an integration error appearing during this code?

I'm really confused about this to be honest. If i evaluate approx[x,k] for some k, and then input the list into the Plot function, I get a plot. But if I try to use approx[x,k] directly, I get an ...
29 views

### How to save data and show step sizes when using components and data structures of NDSolve?

In some applications, it is advantageous to access components of NDSolve. However, we could also need to observe the step size taken in the numerical integration, ...
27 views

### Analytic solution of a system of six ODEs [duplicate]

I have a system of six ODEs for six function. I want to get the analytic solution of the system. I have used DSolve, but it can not solve it. The code is: ...
20 views

### Acquire a single-variable function by slicing a 3d graph along a given line

Consider my Calculus 2 math problem: Given a function f[x,y]=x^2-3xy and two vectors a = {1,2} and b = {1,1}. Spanning a linear ...
151 views

### Who or what is named character Andy?

I suspect \[Andy] meant to represent a staff member, or at least a person of importance. I tried the F1-"Wolfram Search", Wolfram|Alpha and a simple Mma.SE & ...
84 views

### Changing Color of error messages

I would like to change (from the stylesheet) the colors of the error messages. For example, trying to evaluate Solve[wrongsyntax = 0, var] gives an obvious error ...
431 views

### How to generate binary array whose elements with values 1 are randomly drawn

I am trying to generate a binary matrix (whose elements are 0 or 1) of dimension 20x20. To do this, I want to supply as input the number of matrix elements that will take value 1. After, I want to ...
52 views

### How to solve this equation numerically? [on hold]

Two Gaussian functions: f1,f2 of the form f1 = a1*Exp[-t^2/s1^2]. Total area, Atot of (f1+f2) is known. Height of each peak (a1 and a2) is known (experimental ...
65 views

### Running file with some extension

I want to run the Mathematica file with some extension, like '.m'. But, I don't know, how can I run the code. Please, guide me.
54 views

### Efficient Round edition with different rounding direction

As pointed out in this post, Mathematica has a special version of Round that Round rounds numbers of the form x.5 toward the nearest even integer. A comment by ...
51 views

### How do I obtain the characteristics and properties of an alloy? [on hold]

I would like to obtain the characteristics and properties of the Alloy Chromel. How do I download that information from the database of Wolfram Alpha and then print it in a Mathematica Notebook? ...
86 views

### How to solve these ODEs using NDSolve?

I have six odes and I cannot use DSolve. So I tried NDSolve. But it says there may be some errors.The code is such like this: ...
42 views

### Custom alignment for GeoMarkers

I need to align a GeoMarker at the bottom left of the marker: ...
154 views

### Dot product result has wrong dimension

I'm doing a small project and I've encountered a problem while using Mathematica. I should mention that I'm kinda new to this software, so maybe it's just something I haven't grasped yet. Anyway, I ...
69 views

### Unable to evaluate Eigenvalues and Eigenvectors for a matrix (2)

I have posted a similar question last year pertaining to this issue. Here's a link to my post together with the solution given: Unable to evaluate Eigenvalues and Eigenvectors for a matrix I have ...
88 views

### A single argument pattern definition applies to multiple-argument patterns?

Consider defining a pattern rule, such as myFun[x_]:=x As far as I understand Mathematica syntax, this rule means ...
41 views

### Rational numbers treated as symbols? How to query for actual symbols? [on hold]

I have noticed that the following query returns FreeQ[Rational[3, 8], _Symbol] False which can only be explained by the ...
46 views

### Extracting parts of an expression

I have lists with expressions like this one: {-DTMomentum2[{0, 0, 1}], DTMomentum2[{0, 0, 0}]}. DTMomentum2 is just an undefined ...
127 views

### Maxwell construction problem with FindRoot

A Maxwell construction is just an integral of area and then solving for a root to find vapor pressure. This must be exactly the same value as where the Gibbs energy plot crosses at a point. I found ...
49 views

### Solve a complex equation symbolically?

I try to solve this equation symbolically: Solve[A*s - b*Log[Sqrt[(d - e*s)^2 + 1] + d - e*s] - x + b*c == 0, s] (yes: ^2 = cntrl-6) But M. (trial version) is ...
47 views

### Numerical Minimization of Large Expression

I want to minimize a function which contains ArcTan functions. The function is also very complicated. I have the following code. ...
57 views

### How can I add labels to a plot?

I have created five lines in a plot. Plot[Table[1 + (k - 1)*Sin[theta]^2, {k, 0, 2, 0.5}], {theta, 0, Pi/2}, PlotRange -> {{0, Pi/2}, {0, 2}}] And I want to ...
59 views

### Dynamically evaluating integrals where the limits of integration must be found with FindRoot

I've the following problem: I need to use Manipluate to scroll over different values for $\text{R}$ ($0<\text{Rb}\le10^5$) and plotting for values of $0<\text{c}<10$. So, I have the ...
106 views
+150

### Solving for coefficients of a polynomial ansatz in a rational function

Firstly, I apologise for the numerical messiness, and for the extended length of this question. If this is successful, this is the last question I will need to ask for a long time. I start with a ...
73 views

### Design completion idea for Position [on hold]

This is not exactly a question but rather a suggestion for a design which I think would greatly improve Mathematica. Before I put this to Wolfram Research I would like to see what other people think ...
37 views

### Wolfram CDF Player Pro trial license [on hold]

Is there a Wolfram Player Pro trial (e.g. for limited time) license available?
63 views

### Solve nonlinear system with eight variables

Please I realy need Help We consider the three functions H1=4(x+b1 y)^2+8(c1x-d1 y)+e1^2 y^2, with e1>0 H2=4(x+b2 y)^2+8(c2 x-d2 y)+e2^2 y^2, with e2>0 H3=4(x+b3 y)^2+8(c3 x-d3 y)+e3^2 y^2, with ...
56 views

### Finding all positive roots of a transcendental equation [duplicate]

I need to find all positive roots of the following transcendental equation 2*cot(x) = 6.4*x-0.1563/x I know that the roots can be visualised as the intersecting ...
39 views

### Use ParametricNDSolveValue for system of equations

I'm trying to use ParametricNDSolveValue for a system of equations. I want to have it create a function that takes in a single input and outputs a list. Here is my code thus far. ...
107 views

### How to Plot a transcendental function

Let me try to be a bit schematic because my own expression is a bit complicated and could be not useful for future questions. x=f[y*a[x]] My problem is how to <...
56 views

### How to make a 1D VectorPlot

I am trying to use VectorPlot to produce a 1 dimensional vector plot. I Have tried using VectorPoints->{10,1} but it produces ...
521 views

### Unexpected result from ArcLength

I want to determine the arc lenght of a parametric curve $C: \{x(t),y(t) \} = \{ \cos(t)^p , \sin(t)^p \}$ with $p$ between $0$ and $1$, and $t$ between $0$ and $\pi/2$. I set up the following ...
344 views

### Gantt Chart like rectangles with log scale

I need to plot something that looks like a gant chart, but are actual data ranges. These ranges need to be on a log scale. Graphics does not offer a Scalingfunction. A LogPlot with ErrorBars does not ...
88 views

### Substitution in expressions

As the title suggests, I want in an expression to to some substitutions. For example in the expression $\mathcal{L}^+_0+\mathcal{L}^-_0+\mathcal{L}^+_0+\mathcal{L}^-_0+\mathcal{L}_1$ I want to ...
162 views

### Compute a certain “separability probability” via a constrained 4D integration over $[-1,1]^4$

I have employed the GenericCylindricalDecomposition command (applied to $6 \times 6$ "density matrix" positivity constraints) to compute the following expression ...
78 views

### Decimal format in Mathematica exported output

I am using ReadList to read an input file as Table format, and exporting the results. The ...
681 views

### Does Mathematica reuse previous computations?

I am doing an analysis of experimental results in which I need to repeat the same GaussianFilter hundred of times on different data. As explained in the ...
36 views

### AppendTo doesn't update when interacting with PopupMenu

I'm trying to ListPlot a list calculated by the Button called "Plot" with PopupMenu linked ...
47 views

### Plot markers for ListPointPlot3D?

I suffer a little bit of color blindness, that is the reason why I always prefer to have plots with markers instead of different colors. For instance, I do not like the look of this: ...
50 views

### Sum of Roots of a Cotangent equation

I want to reproduce a model calculation, which seemed straight forward, but one piece is puzzling. The (quite simplified) function is: ...
24 views

### Low quality when copying bitmap through Context Menu

The easiest method to share your immediate MMA results to non-MMA users among your peers is to just copy the result onto an email and send it. Figure below shows a ...
26 views

### Variable refactoring and multi-selection

In IDEs like PyCharm for Python, I can select a variable name or method name and it will highlight to show where all I have used it. Also its easy to refactor the names under a given text selection. ...
44 views

### Splitting a general rational polynomial ansatz into powers

EDIT This question is completely wrong and useless. It is mathematically incorrect. I think something like Series is sufficient if you're trying to do something ...
113 views

### How to speed up Voigt profile fits?

Voigt profile fits in Mathematica seem terribly slow. For an example data set with 81 points a corresponding fitting procedures for Voigt fits is >1000 times slower than for Gaussian or Lorentzian ...
I am new and hoping a warm welcome from this platform. I am trying to plot the graph of double series in one variable $$\sum_{k=0}^{\infty} \sum_{j=0}^{\infty} C_{k,j} \exp(- 3^k 1.5^{j} x)$$ ...