mw
发帖数: 525 | 1 hi, math gurus:
I read that it is usurally preferable to inverse the triangle matrix L and U
, rather than the original matrix itself.
but I cannot understand why it is like this
can anyone here give a clue ? thanks a lot ? |
c******m
发帖数: 599 | 2 你如果自己会用手算求逆你就知道了
U
【在 mw 的大作中提到】
: hi, math gurus:
: I read that it is usurally preferable to inverse the triangle matrix L and U
: , rather than the original matrix itself.
: but I cannot understand why it is like this
: can anyone here give a clue ? thanks a lot ?
|
mw
发帖数: 525 | 3 thanks for your suggestion
yes, I know (roughly) how to calculate the matrix inverse manually.
so, do you mean that LU only improves the efficiency? why my impression is
that it is more robust to ill-conditioned matrix?
thanks
【在 c******m 的大作中提到】
: 你如果自己会用手算求逆你就知道了
:
: U
|
s*x
发帖数: 3328 | 4 I guess it is not about efficiency, but precision.
U
【在 mw 的大作中提到】
: hi, math gurus:
: I read that it is usurally preferable to inverse the triangle matrix L and U
: , rather than the original matrix itself.
: but I cannot understand why it is like this
: can anyone here give a clue ? thanks a lot ?
|
mw
发帖数: 525 | 5 can you give more details?
I suppose this should be some sort of "hello world" problems for math
students, right?
【在 s*x 的大作中提到】
: I guess it is not about efficiency, but precision.
:
: U
|
c*******h
发帖数: 1096 | 6 in general no one would like to invert the L or U factors.
when you solve a matrix equation Ax=b, first LU factorize A, then do a
forward-solve on Ly=b followed by a back-solve Ux=y to obtain x.
The LU factorization is equivalent to Gauss elimination.
otherwise, how to compute a matrix inverse?
U
【在 mw 的大作中提到】
: hi, math gurus:
: I read that it is usurally preferable to inverse the triangle matrix L and U
: , rather than the original matrix itself.
: but I cannot understand why it is like this
: can anyone here give a clue ? thanks a lot ?
|
s*x
发帖数: 3328 | 7 try to find help from CS guys on scitific computation/numerate computation.
【在 mw 的大作中提到】
: can you give more details?
: I suppose this should be some sort of "hello world" problems for math
: students, right?
|
