All Questions

129 views

Color lines by angle

I would like to color some lines according to the following color function: ...
31 views

Fitting data with a complex function, but requiring real parameters

I am trying to fit a complex data with a complex function, with the real fitting parameters. I was trying to put there constraints like this, but I got error: ...
60 views

PDE solution does not satisfy Neumann boundary conditions using NDSolve

I am trying to solve the free particle Schrodinger equation in 1D (hbar =1, Energy = 1, mass = 1), But specifying conditions only on x==0: ...
37 views

Specify and rename ticks in FrameTicks

When I plot, I use Frame -> True I would like all ticks on the frame axes to disappear and remain only with two ticks, say, 0.1 on the x-axis and 0.5 on the y ...
119 views

35 views

ParametricNDSolveValue over a region

I'm getting the following behavior I don't understand when using ParametricNDSolveValue over a region. You can reproduce the behavior considering Poisson's equation ...
46 views

Dynamically Update both a HorizontalGauge range and the value

I'm developing a demonstration that allows students to explore the location of a point on a number line simultaneously at various scales. I'll show a very simplified version here to get to the nub of ...
37 views

Specifying temporal precision in DateRange

DateRange inserts undesirable precision: ...
60 views

How to plot 3D maximum and minimum surfaces? [closed]

I want to plot the maximum and minimum 3D surface for the following property: ...
50 views

How can I apply NotebookGet on invisible Notebooks?

My problem might be very specific, but can be quickly explained: First I create an invisible notebook nb by CreateDocument, then i apply NotebookGet on it to see its content, wich works fine! Now I ...
33 views

Solve system of equations derived with the Lagrange approach

I am new here and hopefully you can answer my question. I have to pictures attached. The problem is as follows. I have 4 system equations, derived with the Lagrangian approach. Now I want to ...
30 views

Simulate from an AR(1) process where the parameters vary over time

I would like to simulate from an AR(1) process, where the $\rho$ parameter in the process of the form: $X_t = \rho X_{t-1} + \epsilon_t$ varies over time. The path of $\rho$ and $var(\epsilon_t)$ ...
57 views

Is there an easy way to transform unit vectors from spherical to Cartesian coordinates? [duplicate]

Is there a built-in function on Mathematica that will transform unit vectors from one coordinate system to another? I have a vector expressed in spherical coordinates, and I would like to find the ...
44 views

Differentiation of an unknown function

I have to take the partial differentiation of an unknown function. For example, take the unknown function to be $g(x)$. Then it's derivative w.r.t $x$ is $g'(x)$. By default, Mathematica ...
28 views

NDSolve dependence on initial values

I'm checking some results in this paper and I'm currently having some issues with a numerical integration of a set of differential equations using NDSolve (section 2 and 3.1-3.2 in the paper). I'll ...
56 views

how to remove Null's from output? [duplicate]

I'm a math enthusiast and I'm looking for examples of rare divisibilities, let's look at the following one: ...
28 views

NDSolve — using a PDE solution in another PDE

My problem is to use the numerical solution of a PDE as a function appearing in another PDE. Here is the code solving the first PDE (heat equation in a domain) : ...
51 views

RSolve with conditional equation

I have the following conditional equation: $f(n) = 1+2 f(n/2)$ when n is even $f(n) = 1+f((n-1)/2)+f((n+1)/2)$ when n is odd I want to represent this as a conditional equation to be used in ...
31 views

MMA 10.0.2 Windows x64 Crashes during Find Next/Previous

For the past few weeks, MMA has crashed over a dozen times. It only happens when I'm doing Find Next or Find Previous several times while searching through my notebook. Note that I have at least 2 ...
24 views

Multidimensional Fourier PDE solution and and exact solution are scaled by $(2 \pi)^{2}$

I'm solving a partial differential equation (Stokes equation) in a periodic domain in three dimensions with fourier transforms. I'm using Fourier[] mathematica routines to perform the discrete ...
40 views

Permanently fixing a variable in the function

I need to define a function let's say f[x_, y_] := x^2 + y^2 such that I need to fix one variable (let's take y = a) and to ...
911 views

Finding a function that fits the shape of an image

How can I find a function that fits the given shape of an image? Or instead extract a point set from the shape and then find an interpolating function fits the shape. An example image is attached.
56 views

Patterns for destructuring “Function” function arguments

I want to define a function for finding a Jacobian matrix of pure vector function of vector argument. I try ...
28 views

Resolving a logical statement

I would like to test whether f[n] > 0 and f[n + 1] > 0 implies f[n + 2] > 0. This ...