# All Questions

59,222 questions
1k views

### How can I invert a Laplace transform numerically?

I have a very complicated expression, which I want to transform using the inverse Laplace transform. The built-in function InverseLaplaceTransform doesn't work. So,...
66 views

### Help in advection-dispersion equation using NDSolveValue

i have the advection-dispersion equation: Dz = 0.0000738739; as = 2.21622*10^-6; Dz*D[u[z, t], z, z] - as*D[u[z, t], z] == D[u[z, t], t] The boundary and ...
46 views

### System of coupled differential equations

I am trying to solve the following system of equations, but I get as the output the command itself. ...
29 views

### How to create dynamic PlotLegends?

How to add dynamic PlotLegends to the below code? ...
30 views

### Using Dynamic[] function

I would like to use Dynamic[] to print progress of evaluation of some function, which works quite long. let's say that the definition of ...
40 views

### Mathematica problems [on hold]

What means when this message in mathematica program Factor[Solve[E3 == 0, b2]]={}, such that in the expression of E3 there is b2.
25 views

### Keyed Hash for HMAC SHA256

I'm trying to use AWS REST API's (because I can't rely on AWSLink). The sample C# code from Amazon uses this a lot: ...
180 views

### DotPlot for prime numbers

I was thinking to use a dotplot to give a description of prime numbers. On Wolfram website there is written that each dotplot can be built by ...
92 views

### Inverting the order of a Table - Prime numbers

In a previous post I asked for the possibility to have a binary image of the coprimality inside the natural numbers. The following code ...
138 views

### Plot Ramanujan Primes

I often investigate on Ramanujan primes. Is it possible to apply this procedure described in DotPlot for prime numbers ? I think so but which is the condition I should use? I am trying from several ...
110 views
+50

### Another difficult background subtraction

I'm trying to remove the background but it is removing part of the bag in the foreground (because it is white too): Here's what I've tried: ...
43 views

### VoronoiMesh with custom distance function

I'm failing at reading the documentation. Is there a way to specify the distance function used by VoronoiMesh? As a stripped down example say I have a rank-1 lattice such as: ...
38 views

### How do I divide an integral into parts and sum the total?

I have an exercise looking like this: Analyze the integral $4\int_{0}^{1} \sqrt{1-x^2}\ \tex$ numerically by ng the interval (2,1) into three equal parts, then summarize the integral parts. I just ...
148 views

### Taking the numerator and the denominator

Is there any way to get the Numerator and the Denominator of an expression split in the same way that Mathematica graphically represents it. Say I have an expression: ...
39 views

### Issues solving system of differential equations [on hold]

d = NDSolve [{x''[t] == (x [t] + a[t])/(-2), a''[t] == -x''[t]/2, x[0] == 0, x'[0] == 1, a[0] == 0, a'[0] == 0}, {x, y}, {t, 20}] Keeps returning the error "To ...
39 views

### Identifying total derivatives

I would like to identify which terms in my expression are a total derivative and which ones are not. For expressions in which all terms are a total derivative, one can simply use integrate to find ...
35 views

### How to define multivariable vector funtion?

I would like to define a function of variables having two components as $u(x,y) = (f(x,y),g(x,y))$. I defined such a function as u[x_, y_] := {f[x, y], g[x, y]} ...
13 views

483 views

### Fashion segmentation with a neural net?

I would like to train a network that can parse clothing: Does anyone know of a fashion segmentation network with or without pre-trained weights available that I can use in Mathematica? Update: I ...
36 views

### DistributionFitTest` for 2D data [on hold]

How can I make DistributionFitTest accept 2D data? According to the Documentation - it should be able to accept multivariate data, and the test distribution can be ...
22 views

### Monitoring PolynomialReduce/Alternatives for other CAS packages

I have a large generic polynomial That looks like $N = \sum_{i_1,i_2\cdots}c_{i_1,i_2,i_3,\cdots} {x_{1}}^{i_1}{x_{2}}^{i_2}\cdots$ This could have anywhere between 3000-9000 terms with a maximum ...
39 views

### How do I uninstall an old version of Mathematica?

My SSD is getting full, and while trying to clean it up, I found one of the largest things on here is an installation of Mathematica 10.3. As this is an outdated version, I would like to remove it, ...
24 views

### How do I plot a function that contains variables I have previously defined?

I am trying to plot t as a function of the variable EE which is itself included in variables I have defined. However, when I ...
24 views

### Selecting specific elements of a list

Suppose we have the following list: ...
30 views

### How to force Mathematica not to show the result in numerical format [on hold]

I have a function f[x_] = 4/3 x. However, Mathematica displays it as 1.3333 x. How to force it to display the function in the form 4/3 x?
96 views

### Strange behavior of Out[]

Let's create two notebooks external.nb and primary.nb. Then call the external.nb notebook from the primary.nb and investigate values of Out[ ]. The context of the external notebook is not important, ...
23 views

### Discretize Graphics3D with Scale and Rotate?

How can I discretize a Graphics3D object that makes use of Scale and Rotate? When I try <...
1k views

### Isometric perspective for Graphics3D

Is it possible to render Graphics3D in an isometric projection? I know that the ViewPoint option can be used for orthogonal ...
35 views

### How to compute delta coefficients in mathematica

I want to get delta coefficients calculated. The definition can be found here. However, I don't know what to do with the minus indices. I have tried computing it in a slightly different way, namely: <...
75 views

### Conditional evaluation: black hole cross section

I'm trying to calculate the collision cross section of black holes, more precisely, I want the critical impact parameter $b_{\text{crit}}$ for a given initial velocity $v$ such that, at this speed, ...
44 views

### Update initial conditions recursively/sequentially within ParallelTable using NDSolve

I am modelling 3D motion of particles inside a force-field using second-order coupled PDEs, which I solve from time t=t0 to t=t1 with initial conditions x0,y0,z0. I have a total number of "particles" ...
48 views

### Workbench documentation build fails

My old installation of Workbench went inexplicably wrong, so I tried a fresh install of Eclipse & Workbench. Looks good until I try Documentation Build, when I get the following error: An ...
48 views

### Finding the amplitude of function solved using ParametricNDSolve

I have been trying to find the peaks of a function I have plotted using ParametricNDSolve. I have to find these peaks to calculate the amplitude of all the various waves in the observed output. By ...
35 views

### How to automatically transform Abs[Cos[x]]Sec[x] to Sign[Cos[x]]?

Out of some simplification, the term Abs[Cos[x]]Sec[x] appears. How can I make the code automatically transform ...