**Solve singular linear system**Hi, I'm trying to solve a linear system:
Ax = B, A is a given n by n matrix
It is known that A is singular, and if I give x1=a, x2=b then the solution is unique. How do I solve Ax = B provided x1=a and x2=b in matlab? Thank you.
"Haoran " <chr@cms.zju.edu.cn> wrote in message <k43000$rkg$1@newscl01ah.mathworks.com>...
> Hi, I'm trying to solve a linear system:
>
> Ax = B, A is a given n by n matrix
>
> It is known that A is singular, and if I give x1=a, x2=b then the solution is unique. How do I solve Ax = B provided x1=a and x2=b in ...

**solving sparse singular (linear) system**I seem to remember that in previous version of matlab the backslash
operator would try to give solutions to singular systems...I know I
could just knock out the zero rows and solve that non-singular system
but I kind of (lazily) expect there to be a one-line way to do this
in matlab.
Also, I am actually applying it to large sparse singular matrices so
pinv (pseudoinverse) is no good.
thanks ...
>> A = [ 0 0; 1 0]
A =
0 0
1 0
>> b = [ 0 1]'
b =
0
1
>> pinv(A)*b
ans =
1
0
>> A\b
Warning: Matrix is singular to working precision...

**Which method is used in MATLAB to solve square singular linear systems ?**Hello All.
My question is in the subject. I wonder which numerical technique is used in MATLAB to solve square systems with singular coefficient matrix.
Take e.g. A=[
10 10 1 -18
10 20 18 -34
1 18 29 -29
-18 -34 -29 58];
b=[50 ; 100 ; 90 ; -170];
This 4x4 system has rank 2 and MATLAB returns the solution
>> A\b
Warning: Matrix is close to singular or badly scaled.
Results may be inaccurate. RCOND = 9.148276e-019.
ans =
16.8889
-2.6667
9.8467
5.6705
This is not the least-squares solu...

**Solving a recursive system of 3x3 linear systems...**
Hi everybody,
I'm looking at a recursive system where at each l-th step the three
variables a[i,l] (1 <= i <= 3) have to be solved from a system of three
linear equations involving the previously solved a[i,l+1], ....,
a[i,k] (1 <= i <= 3) (so the iterator l runs back, starting from some
value k). My goal is to find a closed form "direct formula" for the
a[i,l], that is a formula that expresses each a[i,l] in terms of the
starting values a[i,k]'s and the the other known constants involved.
More precisely, the code for finding the first few s...

**Solve Linear system with non-linear constrain**Hello!
I would like to solve the following linear system:
Ax = b, (where A is symmetric)
but I would like to force the absolute value of x to be 1. That is <x,x>=1
How can I do that?
Thanks a lot, and sorry: I am a newbie in optimization.
"Max Brega" <matped@tiscali.it> wrote in message <hb4r52$5uj$1@fred.mathworks.com>...
> Hello!
> I would like to solve the following linear system:
> Ax = b, (where A is symmetric)
>
> but I would like to force the absolute value of x to be 1. That is <x,x>=1
> How can I do that?
> Thanks a lot, an...

**Solving a recursive system of 3x3 linear systems... #2**Hello, apparently my previous email with the same subject wasn't
readable since it contained a bitmap. Here's the text again with a link
to the bitmap file to be viewed in a browser, hopefully this is better:
Hi everybody,
I'm looking at a recursive system where at each l-th step the three
variables a[i,l] (1 <= i <= 3) have to be solved from a system of three
linear equations involving the previously solved a[i,l+1], ....,
a[i,k] (1 <= i <= 3) (so the iterator l runs back, starting from some
value k). My goal is to find a closed form "direct ...

**solve linear system**Dear all, I'm new to Matlab and so probably my question will be 'stupid' for some of you.
I have an ODE system and I want to find the steady state (i.e. dx/dt=0). I think the way to achieve this task is using the symbolic toolbox and solve, but even with a reduced system, I can't get the solution for one of the variable, why?
>> syms xa xb;
eq1=-ReversibleMichaelis_Menten(xa, xb, p(2), p(3), p(4), p(5))*p(1)+ConstantFlux_irreversible_(p(7))*p(1)
eq2=ReversibleMichaelis_Menten(xa, xb, p(2), p(3), p(4), p(5))*p(1)-ConstantFlux_irreversible_(p(6))*p(1)
[xa xb]=solve(eq1,eq2...

**Linear System solving**I have the system of equations Ax=b.How can I solve it for A if I know the x and b matrices??
And can I use the lscov() function too??
Hi Betty,
How many rows and columns in the x and b matrices?
Thanks.
Rick
"Betty Vag" <betty00arg@hotmail.com> wrote in message
news:ievopg$1l9$1@fred.mathworks.com...
> I have the system of equations Ax=b.How can I solve it for A if I know the
> x and b matrices??
> And can I use the lscov() function too??
>
On Dec 23, 10:10=A0am, "Betty Vag" <betty00...@hotmail.com> wrote:
> I hav...

**solving a linear system**Hi everyone,
I have a linear equation of the form Ax = b which I solve for every
pixel in an input image by the brilliant matlab \ operator.
Right now, I am looping and solving for every pixel. The matrix A does
not change from pixel to pixel. Is there a faster, better way to solve
this rather than a loop through each pixel?
For example, I looked at the LAPACK documentation for functions like
sgels, dgesls etc. and it says the following:
"Several right hand side vectors b and solution vectors x can be
handled in a single call; they are stored as the columns of the
M-by-NRHS right hand...