All Questions

0
votes
1answer
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 ...
0
votes
0answers
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?
0
votes
3answers
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...
0
votes
0answers
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 ...
0
votes
0answers
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 ...
1
vote
1answer
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, ...
1
vote
0answers
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: ...
0
votes
0answers
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 ...
10
votes
1answer
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 & ...
3
votes
1answer
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 ...
4
votes
5answers
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 ...
0
votes
1answer
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 ...
3
votes
1answer
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.
1
vote
1answer
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 ...
0
votes
1answer
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? ...
3
votes
2answers
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: ...
6
votes
1answer
42 views

Custom alignment for GeoMarkers

I need to align a GeoMarker at the bottom left of the marker: ...
2
votes
4answers
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 ...
2
votes
2answers
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 ...
4
votes
1answer
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 ...
0
votes
0answers
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 ...
0
votes
1answer
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 ...
6
votes
1answer
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 ...
0
votes
1answer
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 ...
1
vote
2answers
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. ...
1
vote
1answer
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 ...
0
votes
1answer
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 ...
1
vote
0answers
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 ...
1
vote
0answers
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 ...
0
votes
0answers
37 views

Wolfram CDF Player Pro trial license [on hold]

Is there a Wolfram Player Pro trial (e.g. for limited time) license available?
0
votes
1answer
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 ...
1
vote
1answer
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 ...
1
vote
1answer
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. ...
2
votes
1answer
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 <...
1
vote
2answers
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 ...
7
votes
3answers
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 ...
6
votes
3answers
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 ...
1
vote
3answers
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 ...
2
votes
3answers
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 ...
2
votes
1answer
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 ...
7
votes
2answers
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 ...
0
votes
1answer
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 ...
1
vote
0answers
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: ...
0
votes
0answers
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: ...
1
vote
0answers
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 ...
1
vote
1answer
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. ...
1
vote
1answer
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 ...
6
votes
2answers
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 ...
1
vote
1answer
37 views

How to find discrete Z-transform of a list of complex numbers

Can we find the discrete Z-transform of a list of complex numbers in Mathematica? Similar to the function Fourier for the discrete Fourier transform, do we have a ...
1
vote
1answer
57 views

Plotting double series

I am new and hoping a warm welcome from this platform. I am trying to plot the graph of double series in one variable $$ \sum_{k=0}^{\infty} \sum_{j=0}^{\infty} C_{k,j} \exp(- 3^k 1.5^{j} x)$$ ...

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