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2021-10-28 21:12:06 +0100 received badge  Nice Question (source)
2021-10-27 20:55:43 +0100 marked best answer Download mirrors and the Sage-Windows installer

Hi All,

I understand that many download mirrors of SageMath for Windows are inactive, they are stuck at SageMath 9.2, no trace of SageMath 9.3 for Windows or SageMath 9.4 for windows. What is the most reliable and active site to download the latest version of SageMath for Windows?

Thanks,

Daniel Volinski

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2021-10-27 18:14:32 +0100 asked a question Download mirrors and the Sage-Windows installer

Download Mirrors inactive Hi All, I understand that many download mirrors of SageMath for Windows are inactive, they ar

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2021-01-10 11:07:26 +0100 commented answer Integral equation solver

What I'd suggest now is to put this procedure and knowledge into a command so that there will be no need to do it manually. You will just need to write the Integral Equation and use this new command to obtain the required solution. Daniel Volinski

2021-01-09 04:23:46 +0100 commented answer Integral equation solver

Thank you,

I was looking for something like what you see in Solve a Volterra Integral Equation , not something manual as you did but a command that would give the solution once I give the equation.

Daniel Volinski

2021-01-08 11:04:10 +0100 asked a question Integral equation solver

Can Sage solve integral equations (where the unknown is a function and the equation involves integrals), either analytically or numerically?

References:

For example, can Sage solve a Volterra equation of the second kind, such as

y(x) == integrate(exp(x-t)*y(t), t, 0, x)

The solution is expected in the form $y(x) = ...$ where the right hand side is an explicit function of $x$ not involving $y$.

Notice in the example the function $y$ appears in two places, once in the left hand side and the other inside the integral sign.

I am looking for something like what you see in

i.e., a command that would give the solution once I give the equation.

2020-12-19 20:00:04 +0100 asked a question How to install Cadabra2

Hi All,

Forgive me if this question is not appropriate in this forum.

I have installed and used SageMath 9.1 Native Windows.

I would like to know how to install and use Cadabra2 in a Jupyter Notebook.

Is it possible?

Thanks,

Daniel Volinski

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2020-08-29 10:34:23 +0100 commented answer When affine_connection is empty

I would go for something more suave, some kind of error that would not stop the calculation of further cells in the notebook, after all, it is not an error that can cause other errors, you just have to give some content to the affine connection (or the tensor field) and everything should be all right.

2020-08-27 12:28:13 +0100 commented answer unavailable link

I reported it in sage-support

2020-08-27 12:28:08 +0100 commented answer unavailable link

I reported it in sage-support

2020-08-27 09:45:09 +0100 received badge  Popular Question (source)
2020-08-26 20:13:12 +0100 asked a question unavailable link

In the section "Geometry and Topology" on the page

the first link is

:doc:`Euclidean Spaces and Vector Calculus`

which does not link to any file. Please fix this.

2020-08-26 05:48:01 +0100 received badge  Popular Question (source)
2020-08-25 22:25:12 +0100 asked a question When affine_connection is empty

Hi All,

I'm using SageMath 9.1 on Windows Native.

When affine_connection has no content and I display it, I get a ValueError that stops the computation.

M = Manifold(3, 'M', start_index=1)
c_xyz.<x,y,z> = M.chart()
nab = M.affine_connection('nabla', r'\nabla')
print(nab)
nab.display()

IMO it should display something like 'Empty' or 'Null' or '{}' but not an error.

Daniel

2020-08-25 22:12:29 +0100 asked a question Error when I had some show commands

Hi All,

I'm using SageMath 9.1 on Windows Native. I'm using the following documentation file: Curve. If I use the very last two parts of that file:

sage: M = Manifold(2, 'M') # the 2-dimensional sphere S^2
sage: U = M.open_subset('U') # complement of the North pole
sage: c_xy.<x,y> = U.chart() # stereographic coordinates from the North pole
sage: V = M.open_subset('V') # complement of the South pole
sage: c_uv.<u,v> = V.chart() # stereographic coordinates from the South pole
sage: M.declare_union(U,V)   # S^2 is the union of U and V
sage: xy_to_uv = c_xy.transition_map(c_uv, (x/(x^2+y^2), y/(x^2+y^2)),
....:                   intersection_name='W', restrictions1= x^2+y^2!=0,
....:                   restrictions2= u^2+v^2!=0)
sage: uv_to_xy = xy_to_uv.inverse()
sage: W = U.intersection(V)
sage: A = W.open_subset('A', coord_def={c_xy.restrict(W): (y!=0, x<0)})
sage: c_spher.<th,ph> = A.chart(r'th:(0,pi):\theta ph:(0,2*pi):\phi') # spherical coordinates
sage: spher_to_xy = c_spher.transition_map(c_xy.restrict(A),
....:           (sin(th)*cos(ph)/(1-cos(th)), sin(th)*sin(ph)/(1-cos(th))) )
sage: spher_to_xy.set_inverse(2*atan(1/sqrt(x^2+y^2)), atan2(y, x), check=False)

sage: R.<t> = RealLine()
sage: c = M.curve({c_spher: [2*atan(exp(-t/10)), t]}, (t, -oo, +oo),
....:              name='c') ; c
Curve c in the 2-dimensional differentiable manifold M
sage: vc = c.tangent_vector_field() ; vc
Vector field c' along the Real number line R with values on
 the 2-dimensional differentiable manifold M
sage: vc.parent()
Module X(R,c) of vector fields along the Real number line R
 mapped into the 2-dimensional differentiable manifold M
sage: vc.display(c_spher.frame().along(c.restrict(R,A)))
c' = -1/5*e^(1/10*t)/(e^(1/5*t) + 1) d/dth + d/dph

Then the result is fine as it should.

But If I add the following two lines after the definition of c, just to see some results:

print(c)
c.display()

Then the very last command of the file gives me a ValueError:

ValueError: no basis could be found for computing the components in the Vector frame (R, (d/dth,d/dph)) with values on the Open subset A of the 2-dimensional differentiable manifold M

Is this a bug?

Daniel

2020-08-13 00:55:59 +0100 commented answer Sagemanifolds display has deteriorated

I understand. Thanks Eric

2020-08-12 20:13:41 +0100 asked a question Sagemanifolds display has deteriorated

Hi All,

I've noticed a deterioration in the display of objects in SageManifolds, I'm using the following code:

%display latex

R3 = Manifold(3, 'R3', start_index=1, latex_name=r'\mathbb{R}^3')
cartesian3d.<x,y,z> = R3.chart()

omega = R3.diff_form(1, 'omega', latex_name=r'\omega')
omega[:] = (y, z, x)
print(omega)
omega.display()

In SageMath for Windows Native 8.1 the display command would display the Greek letter omega. On the other hand in SageMath for Windows Native 9.0 and 9.1 the display command displays the word omega, not the Greek letter.

Is this a bug?

Daniel

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2020-06-24 19:26:16 +0100 commented question SageMath 9.1 for Windows

Has been more than a month since the release of 9.1 for Linux and there is no release for Windows yet. Is there any change of policy regarding Windows? Have you discontinued SageMath for Windows Native? Thanks!

2020-06-04 13:09:31 +0100 commented question SageMath 9.1 for Windows

I've been using SageMath for Windows Native for two years now, no WSL and no virtualization. Could you please tell me if there is an estimate on the release of SageMath 9.1 for Windows Native? Thanks.

2020-06-04 06:24:22 +0100 commented question SageMath 9.1 for Windows

Because in https://www.sagemath.org/ front page, there is a link to download 9.1!

2020-06-03 21:51:41 +0100 asked a question SageMath 9.1 for Windows

Hi All,

Where can I get SageMath 9.1 for Windows? It does not appear in download mirrors.

Daniel Volinski

2020-05-31 20:31:32 +0100 commented answer abstract index notation and differential geometry

Hi Eric: Where can I download 9.1 for windows?. It does not seems to be in the mirrors!

Daniel Volinski

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