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4 votes

How Can I Relax a Molecule in Mathematica?

Mathematica has a couple of force fields available for relaxing atomic coordinates. For example you can start with ethane in a nearly planar geometry and find a more reasonable geometry via ...
Jason B.'s user avatar
  • 68.8k
0 votes

How to speed up generating and filtering large lists of numbers?

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Dotman's user avatar
  • 456
2 votes

Fixed coordinate is shifting in each frame of the animation

Too long for a comment: @SanGu: Study this code to see the first steps for reducing your second posting by at least 50%: ...
David G. Stork's user avatar
-1 votes

Fixed coordinate is shifting in each frame of the animation

Here is the code, after the implementation of everyone's suggestions. ...
SanGu's user avatar
  • 63
1 vote

Separation of variables

By expanding both equations as differences (assuming to be solved for a zero), taking the common numerators and handling $$(r,\ v_r =\dot r, \ \sin \theta, \ \cos \theta , \ \omega = \dot \theta ) $$...
Roland F's user avatar
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0 votes

How does FindRoot work?

One technique is to use Groebner bases--the analogy of Gaussian elimination in linear systems--to make an equation in x (solve that), use that in the second equation (in x and y)... solve that for y, ...
David G. Stork's user avatar
0 votes
Accepted

Speeding up the nested NIntegration consisted of `Exp' and `Bessel' functions

Following the discussion given in the post some, I guess, evident steps for the experienced users were done. In fact It was possible to speed up the code in approx. 20 times. One was necessary a) ...
seva011's user avatar
  • 316
2 votes
Accepted

Finding the minimum of a multivariate function

Here is a working example. As you did not specify G and M, I choose arbitrary tensors for an example. Also note that I use smaller case variable names as you should in MMA: ...
Daniel Huber's user avatar
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0 votes
Accepted

NMaximize doesn't satisfy constraints

It appears that the feasible set is empty. Indeed, ...
user64494's user avatar
  • 26.7k
2 votes
Accepted

Find the minumum value of an expression

If $a=1$, the function you are trying to minimize looks like this: and it can get infinitely close to the value of 1000. Therefore, the question only makes sense if $a$ and $b$ are integers; and with ...
Victor K.'s user avatar
  • 5,191
1 vote

SpherePoints problem

This is just out of curiosity regarding @DanielHuber comment. If you image the points to be electrical charged and considers the energy, then the configuration with 45 degree rotated faces has lower ...
three777's user avatar
  • 188
1 vote

SpherePoints problem

I hope this picture is self-explanatory. I use the so-called Lambert cylindrical equal area projection which maps the sphere to a cylinder, area to equal area. Please, notice periodicity along each ...
yarchik's user avatar
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