# All Questions

61,565 questions
32 views

### Dynamic not updating InputField

I'm trying to do some interactive fitting of data using an arbitrary number of the same function (a Gaussian in this case). This means that I also have an arbitrary number of variables and constraints....
17 views

### Use FindMaxValue[f[x], x] and get value of x at the maximum [closed]

I want to obtain the maximum value of a function (say f[x]), but also the value of x for which the function is a maximum. Is ...
164 views

### Finding the index of an element to be inserted in a sorted list

I have a sorted list with no duplicates: L = {1, 2, 5, 7, 8} Given an integer n, I want to find the index of ...
61 views

### What does D mean? [closed]

I am using Wolfram Cloud for do my homework. I got the following result from a matrix multiplication. ...
61 views

### Problems with manipulation

I am plotting geodesics on an ellipsoid. My problem is that I cannot do the manipulation, from a, b, c. From the starting point and the initial vector, the manipulation works well, but from the ...
60 views

### ListPlot3D of the results of FindRoot

I have a system of 2 simultaneous equations where i want to calculate the values of Tc and Tc which ranging with the values of two variables which are wfc and V. I tried to evaluate it by using ...
62 views

### Limiting solution space for symbolic algebra problems

I have a system of 12 quadratic equations with 12 variables (x11, x12, x21, x22, x23, x33, p1, p2, p3, ϕ, μ, τ) and several positive constants,w, q1, q2. ... > 0<...
68 views

### Vortex motion equation for flux-flow instability

I am solving the motion equation of an isolated vortex oscillation in a superconductor. I am assuming that the driving force is generated by an RF current oscillating at 1.3 GHz. The main point of ...
41 views

### Testing if a function input is an integer

I am wondering why code like digitback[n_Integer] := Framed[Reverse[IntegerDigits[n]]] can check if the input for the function is an integer (this is the ...
73 views

### Modelling a cylinder

I am fairly new to Mathematica. I am trying to model an ideal cylinder of uniform density of radius R (any arbitrary value) which has a cylinder of radius R/2 missing from it. The resulting solid is ...
29 views

### Problems with creating a matrix with functions

I have a function which gives me all the coordinates of a certain bloc in a lattice (with the help of another function for rows and columns): ...
30 views

### Different styles for different points in ComplexListPlot?

I'd like to use ComplexListPlot to show a point and its image under a complex function, with the point and image having different styles, say different colors. Use,...
27 views

### How to put boundary condition for linear set of differential equation?

I have the following code. ...
90 views

### Problem with my user name

I'm trying to use the new website ("Wolfram Function Repository") and i get the following error: ...
26 views

### ListPlot3D for optimization with varying parameter values

This is a followup question from Alex Trounev's answer to my question in the following post: 3D-Plot optimization results for varying parameter values Consider my objective function, objF: ...
54 views

### Converting Daily Time Series Data into Low Frequency Data (Weekly, Bi-weekly, Monthly,..)

I have daily time series example data as follows: ...
17 views

### How to enhance the precision of the numerical solutions of ODE

Given an ODE $$D f=0$$ over the interval $[x_0,x_1] \subset \mathbb{R}$, where $D$ is a linear differential operator. I can compute the boundary condition $f(x_0)$ to a very high precision, as high as ...
99 views
+100

### NetTrain Freezes Computer

I have a neural network I am trying to train: ...
169 views

### Certain list transform

I imported three lists ...
38 views

### Fitting a Curie-Weiss law function with a diverging point to a data

I would like to fit a function to some experimental data such that the extracted value of Curie temperature (Tc) describes the temperature at which the response flattens out to a constant value. ...
34 views

My code is ...
30 views

### How to plot weighted sum of functions?

Consider a series of functions like Table[Cos[k t], {k, 1, 2, 1/10}] which are summed up together with some weights ...
49 views

### How to fit a list of points to a certain form given error bands?

I am trying to fit a list of points to the form F[0]/(1 - a*q^2 + b*q^4), where F[0] is the value at zero of a function, which ...
40 views

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### Mathematica cannot compile complex-valued interpolated PDE coefficients? (NDSolve, Finite Elements)

Bug introduced in 11.1 or earlier, fixed in 11.3 or earlier. The following PDE pde = I Cos[x y] D[u[x, y], x] + Laplacian[u[x, y], {x, y}] == 0; Is happily ...
40 views

### How to creating a model for prediction disease based on patients symptoms using SVM algorithm [duplicate]

I have a matrix for diseases associated with their symptoms, the columns represent symptoms each row is a disease. the labels 1 and 0 in the matrix data sets represent when a disease_i related to a ...
35 views

### Сontour integral [migrated]

everyone. Can you help with the task?
100 views

### Error messages for FindRoot and NIntegrate

I want to solve the following problem. First, the setup. A function $V(\varphi)$ defined as \begin{multline} V(\varphi)=\frac{\alpha-3}{4}e^{\sqrt{2\alpha}\varphi}+\frac{\alpha-5} {\gamma}e^{(\...
77 views

### Structural Breaks in a Time Series Model

The Chow test is a test of whether the true coefficients in two linear regressions on different data sets are equal. In econometrics, Chow test is most commonly used in time series analysis to test ...
40 views

### Unexpected behavior from Inner[]

Does anyone know why Inner[] behaves differently in the last of these three examples? Inner[f, {a, b}, {e1, e2}, List] ...
74 views

### How can I plot a sphere like the picture in Mathematica?

The coordinate of two points are (0,0,1/3) and (0,0,-1/3) respectively.How can I get this picture in Mathematica?
37 views

### How to use CTensor for the Maxwell stress tensor F?

I have used the CTensor to compute an equation of motion. Everything is ok but the stress tensor F. How can I rewrite this tensor using CTensor. The needed ...
33 views

### NSolve cannot find solution to system of trig equations

I was making a program to convert a rotation matrix to a set of euler angles. I wanted to do this for any valid rotation order that the euler angles were made with, and I did not want to do it the ...
24 views

### How to optimize bin counts with weighted data using multiple lists?

I am trying to sort elements in multiple lists into buckets with weighted data. I can do the single-list case based on a previous question. Specifically, the code under Update in the first answer. <...
58 views

### Five equations to solve 6-variables question, is it possible?

I was given a task to find the value of variable a,b,c,d,e and f. But I'm not sure it is even possible, given that only 5 equations are available. Can anybody point out how to solve these: ...
21 views

### Two coordinate rotations and a translation to for a 4x4 matrix

I am looking to do ewo coordinate rotations and a translation. I'd like the new coordinate system to be shifted by x,y,z (in the directions of the same name) and then rotated by theta in the x hat ...
45 views

### I need the product of two functions be understood as a function itself (a Dirac delta example):

Define: In:= Dirac /: Dirac[x_, y_] f_[x_] := f[y] This works like Dirac's Delta. For example, In:= h[x] Dirac[x,y] Out:= h[y] perfect! However if I ask: In:= h[x] k[x] Dirac[x,y] Out:= h[y] ...
19 views

### CompiledFunction::ctfa - Argument should be a rank 4 tensor of machine-size real number

Dear Mathematica community, I got the following error line: CompiledFunction::ctfa "Argument {<<1>>} at position 1 should be a rank 4 tensor of machine-size real number" This is my function:...
42 views

### Variation of the biharmonic equation with Neumann conditions

I am currently writing a script to plot the solution of a variant of the biharmonic equation. In this case the equation I want to solve is ...
99 views

### Plot vectors as sums of vectors along the axes

in a phase diagram appear vectors that go in different directions. When graphing with the "streamplot" or "vectorplot" command, only the arrows appear showing how they move away from or closer to ...
58 views

### Still having problem with solving high polynomials with exponential equations simultaneously

I need to find the value of Ta and Tc for two simultaneous equations to get a numerical answer using NSolve. I have tried using FindMinimum and NMinimize and still could not solve the problem. Here is ...
148 views

### Generate random non-zero “island” in matrix of zeros

I'm trying to write a code which will generate a 3 dimensional array of 0s, then pick some random location in the array, and subsequently expand contiguously to random neighboring sites until a set of ...