[sage-support] Re: Random sparse matrices over finite fields
On 2/21/07, Iftikhar Burhanuddin [EMAIL PROTECTED] wrote:
Hi folks,
Random sparse matrices over finite fields generated by SAGE do not look
sparse to me. Bug?
sage: Mat(GF(17), 10, sparse=True).random_element()
Ifti,
looking at the docs for random_element(), it looks like you need to
specify another argument to get a sparse matrix:
{{{
sage: MS = MatrixSpace(ZZ,10,sparse=True); MS.random_element (density=0.4)
[ 0 0 0 0 0 0 -2 -1 0 0]
[ 0 0 0 1 -2 0 0 0 0 0]
[-2 1 0 0 0 0 0 0 2 0]
[ 0 -2 1 2 -2 0 0 0 0 0]
[ 2 0 0 2 0 0 2 0 -1 0]
[ 0 0 0 0 1 0 -2 -1 -1 0]
[ 2 0 2 0 0 0 0 2 0 -2]
[ 0 -1 0 0 0 2 -2 0 -1 0]
[ 0 0 0 0 0 2 0 0 0 2]
[ 0 0 0 -2 0 -2 0 2 -1 1]
}}}
This seems somewhat counter-intuitive to me. Maybe there should be a
self._density that gets set to something like 0.3 when
self.__is_sparse is True?
Another idea: maybe we should be able to set the density directly:
{{{
MS = MatrixSpace(ZZ,10,sparse=True,density=0.4)
}}}
although this seems redundant to me...
didier
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[sage-support] Creating table of values in SAGE
I'm trying to pass in an expression to my class Table and use i in the for loop for the x variable. How can I do that? class Table: def __init__(self,range_start,range_end,step,expression): self.range = range(range_start,range_end+1,step) self.expression = expression def __repr__(self): return 'Table of values of %s for %s' % (str(self.expression),str(self.range)) def __str__(self): string = 'x| y\n\n\n\n' for x in self.range: string += '%5d|%6d\n\n' % (x,self.expression) return string table1 = Table(0,10,1,2*x+3) print table1 x| y 0|21 1|21 2|21 3|21 4|21 5|21 6|21 7|21 8|21 9|21 10|21 I created a for loop outside of my class: for i in range(11): x = i print '%5d|%6d\n\n' % (x,2*x+3) 0| 3 1| 5 2| 7 3| 9 4|11 5|13 6|15 7|17 8|19 9|21 10|23 I don't know why x in self.expression equals 10. I have done several tests and found that in my class x always equals 10. You can check that in SAGE notebook 1 history. --~--~-~--~~~---~--~~ 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://sage.math.washington.edu/sage/ and http://sage.scipy.org/sage/ -~--~~~~--~~--~--~---
[sage-support] sage-2.1.4 on pentium4-pc-linux-gnu question
After building sage-2.1.4 on pentium4-pc-linux-gnu, I run 'make test' and get [stuff deleted] sage -t devel/sage-main/sage/rings/real_double.pyx gsl: exp.c:111: ERROR: overfl ow Default GSL error handler invoked. [stuff deleted] Is this a problem? Sage keeps on testing and at the end says All tests passed. But the word ERROR (in capital letters!) has me worried. Kate Minola University of Maryland, College Park --~--~-~--~~~---~--~~ 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://sage.math.washington.edu/sage/ and http://sage.scipy.org/sage/ -~--~~~~--~~--~--~---
[sage-support] Re: Creating table of values in SAGE
I'm not sure whether you've gotten an anwser (my mail feeds are working at cross-purposes right now), but: On Feb 21, 2007, at 10:42 AM, Timothy Clemans wrote: I'm trying to pass in an expression to my class Table and use i in the for loop for the x variable. How can I do that? class Table: def __init__(self,range_start,range_end,step,expression): self.range = range(range_start,range_end+1,step) self.expression = expression def __repr__(self): return 'Table of values of %s for %s' % (str(self.expression),str(self.range)) def __str__(self): string = 'x| y\n\n\n\n' for x in self.range: string += '%5d|%6d\n\n' % (x,self.expression) return string table1 = Table(0,10,1,2*x+3) I believe that you should treat the 'expression' as a function, in that the string you are building up should be done thusly: string += '%5d|%6d\n\n' % (x,self.expression(x)) Hope that works for you. I got a complaint when I tried your example, so I'm not sure how you got this output: print table1 x| y 0|21 [snip] Justin -- Justin C. Walker, Curmudgeon at Large Institute for the Absorption of Federal Funds --- My wife 'n kids 'n dogs are gone, I can't get Jesus on the phone, But Ol' Milwaukee's Best is my best friend. --- --~--~-~--~~~---~--~~ 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://sage.math.washington.edu/sage/ and http://sage.scipy.org/sage/ -~--~~~~--~~--~--~---
[sage-support] Re: Creating table of values in SAGE
Thanks On 2/21/07, Justin C. Walker [EMAIL PROTECTED] wrote: I'm not sure whether you've gotten an anwser (my mail feeds are working at cross-purposes right now), but: On Feb 21, 2007, at 10:42 AM, Timothy Clemans wrote: I'm trying to pass in an expression to my class Table and use i in the for loop for the x variable. How can I do that? class Table: def __init__(self,range_start,range_end,step,expression): self.range = range(range_start,range_end+1,step) self.expression = expression def __repr__(self): return 'Table of values of %s for %s' % (str(self.expression),str(self.range)) def __str__(self): string = 'x| y\n\n\n\n' for x in self.range: string += '%5d|%6d\n\n' % (x,self.expression) return string table1 = Table(0,10,1,2*x+3) I believe that you should treat the 'expression' as a function, in that the string you are building up should be done thusly: string += '%5d|%6d\n\n' % (x,self.expression(x)) Hope that works for you. I got a complaint when I tried your example, so I'm not sure how you got this output: print table1 x| y 0|21 [snip] Justin -- Justin C. Walker, Curmudgeon at Large Institute for the Absorption of Federal Funds --- My wife 'n kids 'n dogs are gone, I can't get Jesus on the phone, But Ol' Milwaukee's Best is my best friend. --- --~--~-~--~~~---~--~~ 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://sage.math.washington.edu/sage/ and http://sage.scipy.org/sage/ -~--~~~~--~~--~--~---
