All Questions

Lately, I have encountered the following problem, namely how to recognize the shapes of particular polygons. I have realized that quite straightforward to do so when the polygons are separated by ...

I am quite new in this field. For my university I prepared a stiffness matrix to solve for a project group. This matrix consists of 450 equations with 450 unknows (it's a Matlab script) and I have the ...

I have N matrices that are positive definite, and I have to solve for a M vectors. As M is large in my case, doing all solves simultaneously using np.linalg.solve ...

I've implemented a code which allow me to find the solution of a perturbed orbit (3-body system) and I was wondering how could I find the numerical error caused by the method I'm using (Runge-Kutta 4)....

How to solve/assess the following problem? Given: $N$ ingredients like apples, bread etc. Mass of an ingredient $j$ is in this simplified model a sum of macro nutrients carbohydrates, proteins and ...

Does anyone know of any published study that talks about the practical aspects of running Adaptive Lagrangian-Eulerian techniques for solid and/or fluid mechanics problems? I'm looking for things ...

While implementing the Multipole-to-Multipole translation (M2M) with the following equation, $$\phi(P) = \sum_{j=0}^\infty \sum_{k=-j}^j \frac{M_j^k}{r^{j+1}} Y_j^k(\theta,\phi)$$ where, $$M_j^k=\...

I am a newbie to convex optimisation and I am learning with the aid of CVXPY. I am requesting for clarity on the illumination problem as described in Boyd & Vandenberghe lecture 1 slides here. I ...

I'm trying to verify the order of convergence for implicit Euler method to numerically solve Black-Scholes PDE. Theory says that it should be $O(\Delta t + \Delta S^2).$ My code is working absolutely ...

I want to simulate the high order harmonics spectrum; target atom is Hydrogen; driving laser is a Ti:Sapphire laser with 800nm wavelength; Its electric field strength is 0.05 a.u.. I do not have cut ...

I am looking for finding or rather building common eigenvectors matrix X between 2 matrices A and B such as : ...

I want to try simulation-(and not experimental)-driven approach to design custom fireplace fuel burners. What software applications, libraries, code and model templates can I use to model and ...

My question is around the efficiency of AMG. In which case AMG can perform better,as solver or as a preconditioner(for example a Krylov space method as CG)? Assume the case of elliptic pdes.

I'm writing a solver (in C) for 3D incompressible fluids, using the finite-differences method, and I'm finding a somewhat surprising behaviour: the solver provides "good-looking" solutions, ...

i trying to solve this integral $$\int_{-\infty}^{\infty} e^{-x^2}dx$$ I'm using this CODE ...

Is there an efficient way to measure similarity/distance between two sequences of ranked numbers/letters. The two sequences are of different length, and only have some elements in common? For example,...

The model is $$y_i=\beta\big(x_{i1}^\alpha+x_{i2}^\alpha+...+x_{im_i}^\alpha\big)+\epsilon_i\textrm{ for }i=1, 2, ..., n$$ I want to minimize the MAE, i.e. $$\Sigma_{i=1}^n{\big|y_i-\beta\big(x_{i1}^\...

[![logical exor funtion][1]][1] I'm done on the first definition where input is two intergers in a logical exor funtion. Now I have no idea on how to do it binary integers in a dynamic array. Please ...

How do I get an .inp file from Gmsh? I need to create a simple geometry and mesh it and define the boundary conditions in Gmsh and export it as an ...

A MATLAB library seems to overcomplicate a computation: exp( (log(a) - log(b))/b ) which is mathematically equivalent (assuming real & positive ...

How frequently scientific code uses comparisons NaN == NaN? Reason of asking: from time to time compilers / software floating-point library implementations have ...

In my research, I need to invert a Fisher matrix in order to get a covariance matrix for me to do parameter estimation. Unfortunately, the values of Fisher matrix vary by many orders of magnitude, and ...

The fortran used come from Montreal Ecole polytechical in 1980 I need some thing that can read fortran and compile it in a Windows 7 or windows 8 operating system.

Even if quad precision is not directly supported by most CPUs, many Compilers (GNU, Intel) support them. Also some software packages allow to compile with quad precision, e.g. PETSc. But is there ...

My PC just broke and I'm looking for a replacement and thinking about getting the Apple Mini M1. But I need to run PLUTO CODE, an numerical hydrodynamics simulation, do anybody knows if this will run? ...

In model predictive control, an optimization problem is solved at every time instant and it is very common to write down the matrices in a compact form. Without going into the details of the ...

I am struggling with implementing an algorithm that does one simple thing: Consider two polygons (one can just draw any two polygons and number their vertices), whose connectivities in a node list are:...

Language: Python3 Problem: I have a matrix Q of shape [51200 rows x 51200 cols] stored in a binary file, each of the element in this matrix has a data type of complex64. To load the data into memory I ...

I am trying to use CVXPY to optimise signal-to-noise-plus interference ratio (SINR) for a visible light communication (VLC) system. I have one of my SINR constraints stated as \begin{equation} \...

I'm in search for a library for solving large systems of non-linear equations, similar to MINPACK, but unlike MINPACK, can accept a Jacobian in band-storage. My Jacobian is sometimes not invertible, ...

Background: I have only built one working numeric solution to 2d Navier-Stokes, for a course. It was a solution for lid-driven cavity flow. The course, however, discussed a number of schemas for ...

I am trying to self-learn SciPy and evaluate the following quadruple integral using scipy.integrate.nquad: $$\int_{0}^{1} \int_{0}^{1} \int_{0}^{1} \int_{0}^{1-x} (...

i am implementing a Matlab code to solve the following equation numerically : $$ (\frac{\partial c}{\partial t} =-D_{e} \frac{\partial^2 c}{\partial z^2} +U_{z}\frac{\partial c}{\partial z}) $$ with ...

I'm very new to computational Physics and am finding conflicting statements on whether the velocity Verlet algorithm, defined as: $\begin{align} x_{n+1} &= x_n + v_n \Delta t + \frac{1}{2} a_n \...

I am trying to implement Poisson image blending as in the paper Poisson Image Editing. This is the task of filling in a masked region of an image by minimizing $$\min_f\int_\Omega \left | \nabla f - \...

Issue description I am working on human brain tACS simulations where I have the models of the skin, skull, csf, brain and ventricles in STL format. The shape does not matter and there are no ...

I am new to fortran and I am trying to write a code using random datas instead of binned datas in x, y, z as shown in my sample code. ...

For a given integer $n\in\mathbb{N}^*$, I want to find a pair $(x,y)\in{\mathbb{N}^*}^2$ such that $x*y=n$ and $|y-x|$ is as small as possible. A naive algorithm I found is : ...

Following the advise of @Federico Polonion a previous post, one suggested, to find a basis of common eigen vectors between 2 matrices, to simply do : Generate 2 ...

I am trying to write a function to compute 1st derivative with backward difference approximation. $ u'(x_i) = \frac{u(x_i) - u(x_i - \Delta_x)}{\Delta x} \equiv D_- u(x_i).$ And for the first point, ...

I am trying to solve a set of ODEs using the Harmonic Balance method. In order to do this, I need to compute the Jacobian of the set of equations. However I am very confused regarding the dimensions ...

I am modelling a problem that is "driven", not by typical boundary conditions but, by contractions in its interior. In a finite element analysis, I can specify the new lengths (not ...

Hi I am trying to solve a set of pde converted into ODE and DAE using central finite difference method. I have used the MATLAB 'solve' command to determine the coefficients of fictitious nodes for ...

I am puzzled by the Wikipedia entry discussing many online algorithms for computing the sample variance, including the Welford's online algorithm. In particular, the sample variance $s_n^2$ can be ...

Do you know any way to call scipy.integrate.odeint, solve_ivp, or any python solver directly within a Matlab code? I have tried ...

I want to plot a numerical integral function of some function $f$ using scipy and matplotlib. How can I do this? I tried the ...

I have been struggling for two days with the following problem. I would like to do a $d$-dimensional interpolation over some data. I tried first to use polyharmonic splines, but when the size of data ...

I am trying to read in a CSV file for one of my boundary condition in OpenFoam, but for some reason OpenFoam is not reading the file. There is no error message or anything, it just not showing the ...

Original Stack Overflow Question: https://stackoverflow.com/questions/65683788/indexerror-index-31-is-out-of-bounds-for-axis-1-with-size-31?noredirect=1#comment116218335_65683788 PDE: u_t = u_xx + u(...

I am using the Galerkin method (Discontinuous to be precise) to discretize in space the scalar linear wave equation and the explicit second order centered finite difference scheme to discretize in ...