Computational Science Questions, Problems & Solutions : TransWikia.com ~ Page 15

Numerical minimization of the action in python

I want to find the trajectory $x(t)$ which minimizes the action $S = int_{t_i}^{t_f} L(x(t), dot{x}(t)) mathrm{d}t$ numerically. I am trying to do it by discretizing the action...

Asked on 07/21/2021 by murt_

2 answer

How can I detect lost of precision due to rounding in both floating point addition and multiplication?

From Computer Systems: a Programmer's Perspective:With single-precision ﬂoating pointthe expression (3.14+1e10)-1e10 evaluates to 0.0: the value 3.14 is lost due to rounding.the expression (1e20*1e20)*1e-20 evaluates to +∞ , while 1e20*(1e20*1e-20)...

Asked on 07/19/2021

2 answer

Where does the floating point error come from? (Finite difference using matrix multiplication versus shifts and adding.)

In Julia it appears that one picks up some error terms when doing finite differences using matrix multiplication versus shifts and addition.julia> n = 10001000julia> hessM = circshift(eye(n),-1) +...

Asked on 07/18/2021 by Willie Wong

1 answer

Going From Blender Structure defined by triangles to full 3D mesh (Using GMSH?)

I currently have created a model airplane in Blender by drawing a closed volume with triangular planes. I want to do a FEM calculation on this object, meaning I need...

Asked on 07/18/2021 by Aleksander Bach Lorentzen

1 answer

Help with Fourier beam propagation method

I am working on implementing the Fourier beam propagation method in C++. I am really more of a programmer than a physicist but I think I have a good...

Asked on 07/17/2021

1 answer

discretizing surface integral using nodal DG method

I am currently learning nodal DG methods, primarily through the book by Warburton, and am a bit confused on how to handle surface integrals using straight edged elements. On...

Asked on 07/15/2021 by David1998

1 answer

Linearising Nonlinear Coupled Partial Differential Equations - Alfvénic Diffusion

I am trying to solve the following coupled partial differential equations with a finite difference scheme:$$partial_tf+vpartial_zf+partial_zfrac{1}{W}partial_zf=0$$$$partial_tW+vpartial_zW-partial_zf=0,$$ where both f and W depend on t and z....

Asked on 07/15/2021 by Hanno Jacobs

0 answer

Forming a particular (averaged) block matrix with numpy

Say I have a set of $n times n$ matrices $A_1, ..., A_m$ as numpy arrays. I'd like to create the block matrix defined below. ...

Asked on 07/15/2021

1 answer

Numerically solving the equation of motion for inflation in cosmology

I want to solve the equation of inflation involving a scalar field numerically using Python libraries such as odeint or scipy. The equation is: $$φ''(t) + 3Hφ′(t) + V′(φ(t))=0,...

Asked on 07/14/2021

2 answer

Classical global estimate for $H^1$ error

I'm having lots of troubles in understanding the proof the estimation of the classical $H^1$ error using finite elements of degree $r$. $$||u-u_h||_{H^1(Omega)} leq frac{M}{alpha} C h^r...

Asked on 07/12/2021

1 answer

Ask a Question

Get help from others!

Computational Science : Recent Questions and Answers (Page 15)

Ask a Question