[sage-support] Localhost startup_token
Hi I’m on a MacBook Pro (IntelCore duo, 2.6 GHz, i5) running on OS X 10.10.5 (Yosemite) and I encounter a problem after upgrading Safari. I was working on Sage-6.4.1 until now and it worked perfectly. But now, I get a window in Safari with "localhost:8080/?startup_token » (what does it mean?) and a list of web links, and my NoteBook doesn’t open anymore. What is the problem? Thank you for your answer Ph Griffiths P.-S. I’m a beginner in programming, so, be patient ;) -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at https://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
[sage-support] Re: Seg fault with determinant calculation
On Sep 22, 4:23 pm, phil [EMAIL PROTECTED] wrote: On Sep 15, 10:26 am, Martin Albrecht [EMAIL PROTECTED] wrote: The original machine I was using was needed for other things. So, I ran it on sage 3.1.2rc4 on sage.math.washington.edu and it completed successfully after 169446 seconds. So, the problem was specific to the setup I was using or it was fixed in 3.1.2rc4. The scaling of the problem seems worse than it should be though. The 9x9 problem takes 40 seconds while the 10x0 problem takes 4236 times longer. That's worse than O(n!) let along O(n^3). If your curious, the test problem is athttp://sage.math.washington.edu/home/fongpwf/sage_work/determinant_10... One more thing I've noticed is that loading the saved result either doesn't work is is extremely inefficient. On Monday, I started up 3.1.2 final and ran load detMp.sobj. It's been rough 3 days and it's still going. This means loading takes longer than the original computation. Phil --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: Seg fault with determinant calculation
On Sep 15, 10:26 am, Martin Albrecht [EMAIL PROTECTED] wrote: On Monday 15 September 2008, phil wrote: I've been pushing the limits of determinant calculation over multivariate polynomial rings. I can calculate determinants of matrices up to 9x9 of the form [[x_0_0, x_0_1],[x_1_0, x_1_1]] (each element is a single unique variable). When I get to 10x10 is runs for a while the crashes with: Unhandled SIGSEGV: A segmentation fault occured in SAGE. This probably occured because a *compiled* component of SAGE has a bug in it (typically accessing invalid memory) or is not properly wrapped with _sig_on, _sig_off. You might want to run SAGE under gdb with 'sage -gdb' to debug this. SAGE will now terminate (sorry). I'll try to reproduce the crash and see what I can do about it. You could help by running sage -gdb (if you have gdb installed) and send me the backtrace off list. Thanks. The original machine I was using was needed for other things. So, I ran it on sage 3.1.2rc4 on sage.math.washington.edu and it completed successfully after 169446 seconds. So, the problem was specific to the setup I was using or it was fixed in 3.1.2rc4. The scaling of the problem seems worse than it should be though. The 9x9 problem takes 40 seconds while the 10x0 problem takes 4236 times longer. That's worse than O(n!) let along O(n^3). If your curious, the test problem is at http://sage.math.washington.edu/home/fongpwf/sage_work/determinant_10_poly.sage Phil --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Seg fault with determinant calculation
I've been pushing the limits of determinant calculation over multivariate polynomial rings. I can calculate determinants of matrices up to 9x9 of the form [[x_0_0, x_0_1],[x_1_0, x_1_1]] (each element is a single unique variable). When I get to 10x10 is runs for a while the crashes with: Unhandled SIGSEGV: A segmentation fault occured in SAGE. This probably occured because a *compiled* component of SAGE has a bug in it (typically accessing invalid memory) or is not properly wrapped with _sig_on, _sig_off. You might want to run SAGE under gdb with 'sage -gdb' to debug this. SAGE will now terminate (sorry). 9x9 matrices only take about 40 seconds. The 10x10 calculation runs for a long time (1 hr) before crashing. This is on 64 bit Ubuntu with the patch in Trac #4068 (http://trac.sagemath.org/sage_trac/ ticket/4068) applied. BTW, what is the underlying algorithm used for the determinants? As I understand it, the naive way is O(N!) while the recursive way is O(N^3) for a NxN matrix. Also, occured is misspelled in the error message. It should be occurred. --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: Seg fault with determinant calculation
On Sep 15, 10:08 am, William Stein [EMAIL PROTECTED] wrote: How much RAM do you have? Write to me off list if you want access to a machine with more :-) Ok. I'll send you an off list message. I'm running Sage on 64 bit Ubuntu installed in a VMWare Infrastructure virtual machine with 6 GB of memory allocated. The underlying physical machine has 8 GB. However, free and top only show about 5 GB of total memory. Some how the kernel does not use all 6 GB that is allocated. --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: efficient determinant of matrix over polynomial ring
On Sep 5, 10:14 am, Martin Albrecht [EMAIL PROTECTED] wrote: sage: %time d2 = R(C._singular_().det()) CPU times: user 0.04 s, sys: 0.01 s, total: 0.05 s Wall time: 0.15 s This seems to scale very poorly with the number of variables. Basically, it's impractical to compute determinants when there are more than 4 variables. Variables Time (seconds) 2 0.05 3 0.71 4 11.65 5 252.53 Sage commands / output: sage: R.a,b = QQ[] sage: C = random_matrix(R,8,8) sage: %time d = R(C._singular_().det()) CPU times: user 0.05 s, sys: 0.00 s, total: 0.06 s Wall time: 0.17 s sage: R.a,b,c = QQ[] sage: C = random_matrix(R,8,8) sage: %time d = R(C._singular_().det()) CPU times: user 0.71 s, sys: 0.00 s, total: 0.72 s Wall time: 1.54 s sage: R.a,b,c,d = QQ[] sage: C = random_matrix(R,8,8) sage: %time d = R(C._singular_().det()) CPU times: user 11.65 s, sys: 0.05 s, total: 11.70 s Wall time: 18.53 s sage: R.a,b,c,d,e = QQ[] sage: C = random_matrix(R,8,8) sage: %time d = R(C._singular_().det()) CPU times: user 252.53 s, sys: 0.07 s, total: 252.60 s Wall time: 329.91 s --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: efficient determinant of matrix over polynomial ring
On Sep 5, 10:14 am, Martin Albrecht [EMAIL PROTECTED] wrote: On Friday 05 September 2008, phil wrote: R.x,y = QQ[] C = random_matrix(R,10,10) Cdet = C.determinant() Here's a workaround: sage: %time d2 = R(C._singular_().det()) Thanks for the tip. After making that change, Sage no longer crashes with an out of memory error on 64 bit Debian. However, I may need to make additional changes. The computation is still going after 3 days. Memory usage is slowly increasing and is now at 6.4 GB. The entries of the matrix are composed of coefficients extracted from some matrix operations on 4 3x3 matrices so there are 38 variables in the polynomial ring. Specifically, if anyone is wondering, I am trying to compute left hand side of equation 7 in Five point motion estimation made easy by Li and Hartley (http://users.rsise.anu.edu.au/ ~hongdong/new5pt_cameraREady_ver_1.pdf). The solver given on Li's webpage using Maple within Matlab to compute the determinant at runtime after the coefficients are given as numbers in the problem. I want to pre-compute the determinant with the coefficients specified by constants. That way at run time all you need to do is evaluate the expression replacing the constants with the numerical values. --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] efficient determinant of matrix over polynomial ring
I have a matrix that is composed of multivariant polynomial entries. I want to compute its determinant. The problem is that it is very slow or runs out of memory. For example, R.x,y = QQ[] C = random_matrix(R,10,10) Cdet = C.determinant() # this line takes a long time If you have more variables, it will run out of memory instead (on a 32 bit installation). Is there a more efficient way to do this? Would using symbolic expressions then coercing back to the polynomial ring be better? Thanks --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Line continuation inside
How can I continue a line inside a ? I want to write something like A.a,b,c = ZZ[] over two lines. After typing A.a,b, \ , the interpreter gives a syntax error message. --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: Accessing terms in an expression
sage: var('x,y')
(x, y)
sage: t = x^2 + y^2
sage: type(t)
class 'sage.calculus.calculus.SymbolicArithmetic'
sage: t._operator
built-in function add
sage: t._operands
[x^2, y^2]
sage: t._operands[0]
x^2
It looks like you can access the expression as a tree of binary
operators and their operands this way.
However, the order of the operands in the tree does not always match
the order when the display the expression. It seems to be related
somehow to how you originally entered and then formed the expression.
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[sage-support] Re: Accessing terms in an expression
On Jul 2, 8:33 pm, Mike Hansen [EMAIL PROTECTED] wrote:
sage: var('x,y')
(x, y)
sage: t = x^2 + y^2
sage: type(t)
class 'sage.calculus.calculus.SymbolicArithmetic'
sage: t._operator
built-in function add
sage: t._operands
[x^2, y^2]
sage: t._operands[0]
x^2
How can I do comparisons on the operator? I need to test the operator
so that I only split on additions and subtractions. Also if it is
subtraction, I need to negate the second term.
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[sage-support] Accessing terms in an expression
I've looked around in the documentation but have not been able to
figure out how to access individual terms in an symbolic expression.
For example:
var('x,y')
t = x^2 + y^2
How do I access the first term in t? I want to assign it to another
variable, like first_term = t.extract_term(t,1) to get first_term to
be x^2.
Thanks
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