Emil Widmann's profile - activity

Vielen Dank! I would upvote 2 times more if I could ...

Just 2 more questions: How do I insert latex code here in this forum? How are the symbols D0 and D0,0 defined (result from show(divG), divG in the first version as function from r)?

great, thanks!

Thanks a lot for showing me. - I got the first term of the solution by hand, but missed the second. The result has a meaning, but what it is I have to figure out, it seems the bracket contains sort of a "density operator".

I can do

f(a,b) = a^2+b^3; f=f-f.subs(a=(a-1))
(a, b) |--> -(a - 1)^2 + a^2

I tried to write a function which does this for arbitrary expressions and variables

def test(self, symb):          
    return (self-self.subs(symb=(symb-1)))

but

test(f,a)
(a, b) |--> 0

fails miserably. It seems self.subs(symb=(symb-1)) can not be evaluated properly. How can I achieve what I want?

I have

m = function('m')(r)
V = function('V')(r)
phi = m(r)/r
V = 4*pi*r^3/3
divG = (diff(phi,r,2)+2/r*diff(phi,r)).full_simplify()

which describes a spherical symmetric source term of a field, nice. Now I want to get this as a function of volume, not of radius and tried:

a=divG.subs(r=V(r))

But it gets me nowhere - It should also substitute the differentials - How to solve this?

Hi Emil,

this is due to a logical bug in the atlas spkg: the system-wide variable SAGE_FAT_BINARY currently takes precedence over the specific variable SAGE_ATLAS_ARCH as explained in the trac ticket http://trac.sagemath.org/sage_trac/ti...

A possible workaround until it is fixed is:

• cd ${YOUR_SAGE_ROOT}/spkg/standard/
• tar xvf atlas-3.8.4.p1.spkg
• modify atlas-3.8.4.p1/spkg-install according to the proposed patch http://trac.sagemath.org/sage_trac/at... (this is around line 203).
• tar cvf atlas-3.8.4.p1.spkg atlas-3.8.4.p1
• compile as usually exporting SAGE_FAT_BINARY='yes' and SAGE_ATLAS_ARCH='PIII'

Ciao, Thierry

Hi Thierry - thanks for that explanation! I will keep this in mind and when the time is ripe I will update the Live CD accordingly... cheers emil

Hi, I recently compiled a new version of the Sage Live CD. In older versions it was enough to set SAGE_FAT_BINARIES='yes' to create a binary with low requirements on processor instructions (like "sse2" instruction set).

In the newer versions I also used SAGE_ATLAS_ARCH='base' flag, but now I have a report that it is not working properly on an old pentium processor.

I read something in the sage-devel group that there might be some interference between those build flags. What is the present procedure to produce a true "fat" binary which should run on possibly the widest range of hardware (without having to grant to use modern hardware to full extend).

thanks

Could you provide more specific information? Which Version of Virtual Box did you install? Did you follow the procedure in the Online documentation Sage Appliance Doc? Is it really a black screen or do you have some text on it (e.g. you mention the prompt for login?) Is it possible that you use an older version which is server only? - In this case you access the sage notebook from the windows browser (localhost:8000) best regards Emil

Happy it worked ;-). The above procederes might be necessary if you you wan't to upgrade to a new virtual machine (without the built in upgrade mechanism of sage).