# All Questions

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51 views

### Lanczos memory complexity for dense matrices

Does the Lanczos algorithm remain memory efficient even if the original Hermitian matrix is dense?
67 views

### One of the variables in scipy.optimize.minimize does not get solved

Three variables are declared in the function but scipy.optimize.minimize only solves the first two under the minimization of objective, don't know why. The original ...
33 views

### Which type of RNG can I use together with a MT RNG in a simulation?

This question arises from my attempt to mix two different RNGs. I'd like to mix them choosing the best of the two according to the operations I need to carry out to achieve better performance. I'm ...
• 111
40 views

### Integration of a singular kernel function over a triangle

Problem: I am currently trying to integrate a singular kernel function of the type $$G(x,y)=\frac{\exp(ik||x-y||_2)}{4\pi ||x-y||_2}$$ which lies at the centre of a triangle, over this triangle. $i$ ...
• 101
71 views

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### 2D wave equation is numerically unstable using Finite Difference Method

I'm working with simulating both the heat and wave equation in 2D in a Python code. When simulating the heat equation, I learned about the CFL which I used to get a numerical stable solution. I found ...
• 101
23 views

### GNU Octave toolbar icons [closed]

Is it possible to customize the toolbar icons, i.e. change the default icons with something different? An example could be the use of Fluent icons instead of the default Tango icons.
107 views

• 809
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### unconditionally stable schemes better than conditionally stable ones in accuracy?

Let's consider two finite difference schemes for PDEs/ODEs. One is conditionally stable, the other is unconditionally stable. People always prefer unconditionally stable ones to conditionally stable ...
• 187
39 views

### Delaunay-based isosurface extraction vs marching cubes

I recently tried the isosurface extraction algorithm provided by the C++ library CGAL. This is new to me. It is based on Delaunay triangulations. I have some experience with the marching cubes, I ...
32 views

### In "scipy.integrate.odeint", what does the option "col_deriv : bool, optional" imply?

For example, if I have a matrix differential equation; $\frac{\partial y}{\partial t}=A(t).y$. Here my jacobian is the A(t) matrix. But what is derivative across the column or derivative across the ...
1 vote
77 views

### Conceptual doubt regarding 2D conjugate heat transfer modelling (COMSOL and Mathemtica)

I have been dealing with some conceptual flaws in my understanding of modelling, which I will elaborate herein. I am modelling conjugate heat transfer of a reciprocating fluid, which flows with ...
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23 views

### snappyHexMesh not meshing correct region

I created a simple model of cylindrical container to perform heat transfer simulation using FreeCAD for CAD modelling. I exported the model in stl format along with domain boundaries and faces. I have ...
46 views

### Fortran - Lid-Driven Cavity Boundary Conditions Error when using SIMPLE method

I am studying Numerical Methods for incompressible flows. part of the tasks is to model the lid driven cavity problem in 2D using the SIMPLE method. I have been provided with Fortran code that is ...
33 views

### books/paper recommendation on computational thermal-turbulence by using FEM

I have just learned basic FEM for 2D N-S euqation, now my teacher let me to do the following problem, the document of this problem is in large fluid problem, the system of equations is listed in that ...
• 11
206 views

### Is it really necessary to solve a system of linear equations in the Finite Element Method?

When we solve some boundary value problem by Finite Element Method, the appropriate system of linear equations is built, $$Ax=b.$$ Usually we use the solution x just for plugging it into some ...
1 vote
50 views

### Exponential Integrator to solve PDE with Stiff term

I wish to solve an equation like the following, $$\frac{\partial f}{\partial t}+\frac{\partial}{\partial x}\left(A(x)f\right)=S(x,t)f$$ where $A(x,f)f$ and $S(x,t)f$ are the advection and the source ...
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