On 7/26/07, David Joyner <[EMAIL PROTECTED]> wrote:
> On 7/26/07, mak <[EMAIL PROTECTED]> wrote:
> > 1. How do I change the entire row or column of a matrix at once? In
> > pari, I could do e.g. a=[1,2,3;4,5,6], and then put a[1,]=[0,0,0],
> > which would give a=[0,0,0;4,5,6]. What's the sage equivalent?
There is no SAGE equivalent yet. David's example might be helpful
below though. The best you could in SAGE is set each entry
one at a time right now. I should add something.
def set_row(A, r, v):
for i in range(A.ncols()):
A[r, i] = v[i]
I'm not sure how we forgot to ever do this. I've added this
to the trac server:
http://www.sagemath.org:9002/sage_trac/ticket/405
> sage: a=[[1,2,3],[4,5,6]]
> sage: A = matrix(a)
> sage: A
>
> [1 2 3]
> [4 5 6]
> sage: a[0] = [0,0,0]
> sage: A = matrix(a)
> sage: A
>
> [0 0 0]
> [4 5 6]
>
>
> >
> > 2. I enter a 100x100 matrix and the notebook doesn't display it; I
> > just get something like '100x100 matrix with integer coefficients'.
> > I'd like the matrix displayed explicitly (at my own risk). Clicking
> > to the side doesn't have any effect.
If a is the matrix do
print a.str()
and you'll see it all.
Doing
show(a)
in the notebook might also be useful.
Also, doing
print a[5]
would show you just the 5th row
and print a[:5].str() the first 5 rows (I think).
>
> I don't know. Maybe something like this would help:
>
>
> sage: MS = MatrixSpace(IntegerModRing(5),100,100)
> sage: A = MS.random_element()
> sage: A.matrix_from_rows_and_columns(range(10), range(20,38))
>
> [1 2 4 3 2 1 1 2 4 3 4 1 1 2 4 1 1 3]
> [4 1 3 4 1 0 0 1 1 0 0 4 2 0 1 0 0 2]
> [1 0 0 1 2 2 1 1 3 0 0 0 2 2 1 1 2 1]
> [4 1 3 4 1 2 1 0 1 2 3 3 1 2 2 1 3 3]
> [3 4 0 2 1 4 1 1 1 1 0 1 3 4 1 4 1 0]
> [1 1 2 0 3 3 0 1 0 4 3 2 3 1 3 4 3 3]
> [0 0 1 1 0 0 2 3 2 4 2 4 3 2 1 3 2 2]
> [3 2 1 4 1 2 2 3 1 0 1 2 1 0 3 0 1 3]
> [1 3 0 2 2 1 3 4 3 0 3 0 2 2 0 0 0 2]
> [2 0 0 4 3 4 4 3 1 0 4 3 4 0 3 0 2 0]
>
>
>
> >
> > Thanks,
> > Mak
> >
> >
> > >
> >
>
> >
>
--
William Stein
Associate Professor of Mathematics
University of Washington
http://www.williamstein.org
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