All Questions
88,727
questions
0
votes
0
answers
44
views
Why do the solutions from the FindMinimum produce a lot of unphysical oscillatory points?
The parameters. Here I mention all the parameters I use in my code including some of the functions that I define for convenience
Parameter set-I
...
0
votes
0
answers
23
views
Using a discrete ColorFunction [closed]
I'm finding strange behavior with ColorFunction. Say I want to color a plot to indicate the sign of abscissa (this is a simplification of a more complex plot I'd like to do):
...
- 1,706
2
votes
1
answer
48
views
Plotting image a set under perspective transformation
I want to plot the following set in Mathematica:
$$\{ (x_1, x_2)/x_3 \mid (x_1-3)^2 + (x_2-3)^2 + (x_3 - 3)^2 \leq 1\}.$$
In other words, this set is the output of applying the perspective function $f(...
- 419
0
votes
1
answer
63
views
Poorly behaved ContourPlot
I am interested in finding the interested in finding the intersections of the curves f1==0,f2==0 and g==0 (defined below). My ...
- 305
2
votes
0
answers
77
views
How to write 2D finite volume solver in a functional approach?
I'm solving 2D poisson problem of a finite volume problem using TDMA.
The solution of the problem is given:
\[Phi][x_, y_] := x^2 y + x y^2 + 1
The definitions are ...
- 41
3
votes
0
answers
85
views
Fast approximations of Lyapunov exponents in Mathematica
I have $x_i$ sampled IID from $\mathcal{D}$=Gaussian in $\mathbb{R}^d$ with 0 mean and diagonal covariance $H=\operatorname{diag}h$ and need to find the largest value of $\alpha$, such that the ...
- 6,837
6
votes
3
answers
230
views
Apply pattern using a Slot (#) to each list element using a second slot
I am trying to find a neat way of applying an operation to each list element, but do not know how to properly use multiple slots or whether it is actually possible to solve this with multiple slots.
I ...
3
votes
1
answer
115
views
Troubling using the arnoldi method
I have the following code:
The first part is just defining the matrices, the error is at the end of the code.
...
- 33
0
votes
0
answers
50
views
How to find output response of filter circuit if transfer function is too complex?
I want to find unit step response of this transfer function. But I think, there is a problem, mathematica is not given any solution. Can anybody give me suggestion how to get the output response?
<...
2
votes
0
answers
102
views
Simplify or FullSimplify doesn't work on Gamma function [migrated]
I have this expression:
Gamma[n - 0.691 + 2.35 I] Gamma[n - 0.691 - 2.35 I]
which returns real values for all $n$. However, neither Simplify nor FullSimplify can ...
user91875
3
votes
1
answer
81
views
Steady state fluid flow for downward flow past an obstacle
I was attempting to simulate fluid flow past a circular obstacle. The following is the code which I used
...
- 33
1
vote
0
answers
69
views
Unable to solve Delay PDEs Error in Boussinesq Approximation
I'm trying to solve the set of equations below describing the flow of a pot of water being heated slightly. The equations are 2D axisymmetric in nature.
...
- 103
0
votes
0
answers
45
views
How can I let each input show its number?
The problem I'm facing is that I want to know number of one input. For example, In[1]:= (...) then I know this is first input, but I found only the first input in a ...
- 1
0
votes
0
answers
23
views
Set TeXForm for user-defined functions [duplicate]
I defined a function gamma in short for a long function.
Now I have an expression (just an example here)
...
- 153
0
votes
0
answers
98
views
0
votes
1
answer
60
views
How to generate the set of lines orthogonal to the mid points of a non-intersectional polygon
Given a set of N = 10 points that in a known order form a non-intersecting polygon take the line orthogonal to a mid point of a line segment, using the first segment for example, and extract the ...
- 403
0
votes
0
answers
40
views
How can we calculate an integral when Integrate does not converge? [closed]
I tried to calculate the probability density of a wavefunction, but got not result. Does anyone have an idea of an alternative approach to get the probability density of it?
Here are the details:
<...
- 989
3
votes
1
answer
47
views
AceGen/ AceFEM: Wrong number of nodes?
I am trying to create an element T1 (linear triangle) to solve the steady, incompressible Navier-Stokes equations. Therefore, my SMSTemplate command reads as follows
...
- 95
0
votes
0
answers
26
views
Does Readlist give maximum its speed?
Trying to understand if ReadList can be seed-up. I have a text file with columns of strings and numbers, some of numbers are in Fortan form. To import that in ...
1
vote
0
answers
36
views
How to keep data/tables stored in Mathematica notebooks for use when reopening the notebook? [duplicate]
When we create a table in Mathematica, can we keep it stored in the Noteboook for use when we reopen the notebook? I know I can export to a CSV or other filetypes and import whenever I need and I know ...
- 5,061
2
votes
1
answer
163
views
Solving analytical integral
I am trying to solve the following integral
\begin{equation}
\left[\int_{0}^{t/2}d\tau-\int_{t/2}^{t}d\tau\right]\left[\int_{0}^{t/2}d\tau'e^{-\left|\tau-\tau'\right|/\tau_{c}}-\int_{t/2}^{t}d\tau'e^{-...
- 573
0
votes
0
answers
43
views
How can I upload a package which is saved locally as a ZIP file to Mathemtica Cloud and Load the package?
I am using the online Mathematica Cloud. I have one complete package(in this case, a group theory-related mathematics package), which is saved locally as a ZIPed folder. The ZIPed folder contains ...
- 1
1
vote
1
answer
87
views
Periodic boundary condition conflicts with DirichletCondition?
I want to solve a simple diffuse equation in a cylinder.
$\nabla\cdot(\hat{c}\nabla\rho_P）=0$
$\rho_P(x,y,\theta)==0,\sqrt{x^2+y^2}=R$
$\rho_P(0,0,\theta)==1,\sqrt{x^2+y^2}=0$
$\rho_P(x,y,2\pi)=\rho_P(...
- 85
0
votes
0
answers
28
views
How to plot the input to a state-space closed loop model?
I have a mathematica notebook to build the state-space model of a system from its differential equations, calculate LQR gains and simulate the system response.
...
- 101
4
votes
3
answers
295
views
Is there a better way to control "Filling"?
I wrote the following code and it works well; however, along the horizontal axis observe the "reddish" line along the interval [0.25,0.75]. It is coming from the CC = line in the code. Is ...
- 1,393
0
votes
0
answers
31
views
Can I define relations without explicit transformation rules?
Is there an alternative way to use Mathematica for symbolic algebra, where instead of defining explicit transformation rules into 'canonical form', I can instead 'gently inform' Mathematica about ...
- 1,079
3
votes
2
answers
82
views
Issue with unit conversion
I am getting an error converting energy unit Pa*m^3 (Pascal * Meters^3) to J (Joules).
...
- 109
2
votes
4
answers
264
views
Evaluate using Mathematica or otherwise the value of $f'(0)$
If we have$$f(a)=_3F_2\left(\frac{1}{2},\frac{a+1}{2},\frac{a+2}{2};
\frac{a+3}{2},\frac{a+3}{2};1\right)$$
where $a\geq 0$ and $_3F_2$ is the Hypergeometric function with unit argument.
Evaluate ...
- 97
0
votes
0
answers
32
views
Solving 2D Poisson Eq with Dirichlet BC's in Python [closed]
Question:
I am trying to solve the following PDE:
...
- 141
1
vote
1
answer
63
views
How to speedup integration of interpolated function with logarithmized data?
Consider some dataset corresponding to the grid x1, x2, function[x1,x2]:
...
- 5,112
2
votes
0
answers
54
views
Argument value loss using Listable C-Compiled Function
In my recent studies, I have come across a very strange anomaly with C compiled functions. When I call a function that has the 'Listable' attribute while global variables are accessed through ...
2
votes
2
answers
112
views
Series expansion using binomial theorem in Mathematica
The series expansion of $\displaystyle\left(1-\frac{a}{x}\right)^{1/3}$ using the Binomial theorem is given by
$$\displaystyle\left(1-\frac{a}{x}\right)^{1/3}=1-\frac{a}{3x}-\frac{a^{2}}{9x^{2}}-\...
- 159
3
votes
2
answers
112
views
How to make appear different labels to different point in the same graphic? [closed]
I am having some trouble to make a graph where there are three data points with x-error bars and I wanted to label each point. I managed to make the first label (the purple one) to appear but I didn't ...
0
votes
0
answers
27
views
How to use the OutputResponse function with multiple inputs?
I have a state-space model with 2 inputs and 2 outputs.
The documentations of mathematica to obtain the output response define the usage as ...
- 101
0
votes
0
answers
37
views
How to set reference value a State-Space Model with simulating the reponse?
I have a mathematica notebook to build the state-space model of a system from its differential equations, calculate LQR gains and simulate the system response.
...
- 101
0
votes
0
answers
26
views
NDSolve coupled ODEs with data
If I have a system of coupled ODEs, say { x'[t]=expr1[x,y,z] , y[t]=expr2[x,y,z],with proper initial conditions } , along with a set of data of (y,z) in the whole relevant region we want to study. ...
8
votes
2
answers
1k
views
Why does Mathematica take so long to produce this sound?
Mathematica is behaving very slow, but it is not like I could compare, as the speed has always been like this. The following ran in 58.64 seconds. Is this normal? How can I speed it up?
...
- 83
2
votes
0
answers
54
views
Mathematica unable to realize simple distributional relationship
I was trying to find the CDF for the following problem:
...
- 493
0
votes
0
answers
49
views
Who can share me the Signals and Systems Package? [closed]
Dear friend in this community，
Recently, I'm studying Pro. Lutovac's "Filter design for signal processing". Direct running his MMA codes in the book needs an obsolete third-party package SSP(...
- 1
4
votes
2
answers
276
views
Solving PDE with Dirichlet, Neumann and Boundary conditions
I am trying to solve the following PDE:
$$
u_{xx} + u_{yy}
=
\begin{cases}
- \cos(x) \quad -\pi/2 \leq x \leq \pi/2, \\
0 \quad \text{otherwise}
\end{cases}
$$
The domain is $\Omega = [-\pi,\pi] \...
- 141
2
votes
1
answer
106
views
Another solution to a simple DE given by DSolve: not the one I expected
Consider a simple 2nd-order differential equation with a parameter $a$, which can be solved with DSolve:
...
- 1,217
0
votes
0
answers
38
views
Efficient evaluation of vector inner products [closed]
I have a situation where I'm trying to quickly evaluate elements of some matrix products. Let $A, B$ be two Hermitian random matrices, and suppose that we have solved the eigenvalue problem for $A$. I ...
- 647
0
votes
0
answers
34
views
How to set the term transfer rule of the equation? [closed]
In the following cases, the root sign, polynomial and constant terms need to be automatically identified, not manually entered. Ensure the universality of the code.That is to say, change the equation. ...
- 793
0
votes
0
answers
26
views
is there anyway to solve the IDE? [closed]
I am completely new to matlab or any math softwares.I came up with this equation when trying to model a man walking through a door with a damper and constant resistive torque (not really sure if it is ...
1
vote
0
answers
20
views
How to make the Levi-Civita express the value from the package xAct?
I try to use the package xAct to compute the 1-form field from 3-form field as shown in the picture below. However, the value of Levi-Civita or epsilong does not express. How could I solve this?
...
- 11
0
votes
1
answer
38
views
Solving series solution of differential equation
AsymptoticDSolveValue[2x*y''[x] -(3+2x)*y[x] +1 == 0, y[x], {x, 0, 5}], this differential equation command, is not outputting the correct solution. The solution should be like y=C1(1+(1/3)x-(1/6)x^2-(...
5
votes
3
answers
217
views
Plot diagonal lattice path
I'd like to plot lattice paths like RUURUD where R is a step to the right, U is a step above ...
- 53
2
votes
1
answer
28
views
Using NMinimize for a real-valued function of complex variables
I am trying to use NMinimize to minimize a real-valued function of complex arguments, with a supplied initial point. This doesn't seem to work well. For example, the following gives errors like "...
- 191
0
votes
0
answers
42
views
How to simplify the formula under the quadratic root sign? [duplicate]
The following formula is given：
...
- 793
0
votes
0
answers
19
views
Smoothening noisy distributions to learn eigenvalue statistics
I have a problem involving random matrices, in which I'm trying to learn properties of their spectral statistics. The problem I'm having can be boiled down to a list management issue, but I will begin ...
- 647