MATLAB Central Newsreader - pinv

pinv

munir — Wed, 04 Nov 2009 21:57:01 -0500

hi all
i want to find inverse of a matrix. but it is singular.so i used pinv.
but some error is occuring. i m not understanding its meaning n what
corrective actions has to take.
??? Error using ==> sym.svd
Too many input arguments.

Error in ==> pinv at 29
[U,S,V] = svd(A,0);

Error in ==> Untitled17 at 238
o = pinv(l)

plz help me out.
thanks and regards

Re: pinv

ade77 — Wed, 04 Nov 2009 23:18:01 -0500

>
> Error in ==> pinv at 29
> [U,S,V] = svd(A,0);
>
> Error in ==> Untitled17 at 238
> o = pinv(l)

can you include the matrix in question

Re: pinv

munir — Thu, 05 Nov 2009 08:30:08 -0500

On Nov 5, 4:18 am, "ade77 " <ade1...@gmail.com> wrote:
> > Error in ==> pinv at 29
> > [U,S,V] = svd(A,0);
>
> > Error in ==> Untitled17 at 238
> > o = pinv(l)
>
> can you include the matrix in question

this is the type of matrix which is singular.it is much smaller than
what i ll be using.
keeassembly =
[ 250*pi*ep33s, 0, 250*pi*ep33s, 0]
[ 0, 250*pi*ep33a, 0, 250*pi*ep33a]
[ 250*pi*ep33s, 0, 250*pi*ep33s, 0]
[ 0, 250*pi*ep33a, 0, 250*pi*ep33a]

plz help. thank u.

Re: pinv

munir — Thu, 05 Nov 2009 08:31:49 -0500

On Nov 5, 1:30 pm, munir <munirpans...@gmail.com> wrote:
> On Nov 5, 4:18 am, "ade77 " <ade1...@gmail.com> wrote:
>
> > > Error in ==> pinv at 29
> > > [U,S,V] = svd(A,0);
>
> > > Error in ==> Untitled17 at 238
> > > o = pinv(l)
>
> > can you include the matrix in question
>
> this is the type of matrix which is singular.it is much smaller than
> what i ll be using.
> keeassembly =
> [ 250*pi*ep33s, 0, 250*pi*ep33s, 0]
> [ 0, 250*pi*ep33a, 0, 250*pi*ep33a]
> [ 250*pi*ep33s, 0, 250*pi*ep33s, 0]
> [ 0, 250*pi*ep33a, 0, 250*pi*ep33a]
>
> plz help. thank u.

where ep33s ep33a will be input values.

Re: pinv

Steven Lord — Thu, 05 Nov 2009 15:31:54 -0500

"munir" <munirpansare@gmail.com> wrote in message
news:19fa6366-f064-4679-824f-fabe56ce387c@u36g2000prn.googlegroups.com...
> On Nov 5, 4:18 am, "ade77 " <ade1...@gmail.com> wrote:
> > > Error in ==> pinv at 29
> > > [U,S,V] = svd(A,0);
> >
> > > Error in ==> Untitled17 at 238
> > > o = pinv(l)
> >
> > can you include the matrix in question
>
> this is the type of matrix which is singular.it is much smaller than
> what i ll be using.
> keeassembly =
> [ 250*pi*ep33s, 0, 250*pi*ep33s, 0]
> [ 0, 250*pi*ep33a, 0, 250*pi*ep33a]
> [ 250*pi*ep33s, 0, 250*pi*ep33s, 0]
> [ 0, 250*pi*ep33a, 0, 250*pi*ep33a]

You can't invert this matrix; rows 1 and 3 are identical, as are rows 2 and
4. This means it's not full rank and so has no inverse. PINV won't help
either -- it's intended for numeric matrices, not symbolic matrices.

If you're trying to invert the matrix in order to solve a system of
equations, DON'T, repeat DO NOT INVERT IT. Instead use backslash (\) to
solve the system directly.

--
Steve Lord
slord@mathworks.com
comp.soft-sys.matlab (CSSM) FAQ: http://matlabwiki.mathworks.com/MATLAB_FAQ

Re: pinv

munir — Thu, 05 Nov 2009 17:59:32 -0500

On Nov 5, 8:31 pm, "Steven Lord" <sl...@mathworks.com> wrote:
> "munir" <munirpans...@gmail.com> wrote in message
>
> news:19fa6366-f064-4679-824f-fabe56ce387c@u36g2000prn.googlegroups.com...
>
>
>
>
>
> > On Nov 5, 4:18 am, "ade77 " <ade1...@gmail.com> wrote:
> > > > Error in ==>pinvat 29
> > > > [U,S,V] = svd(A,0);
>
> > > > Error in ==> Untitled17 at 238
> > > > o =pinv(l)
>
> > > can you include the matrix in question
>
> > this is the type of matrix which is singular.it is much smaller than
> > what i ll be using.
> > keeassembly =
> > [ 250*pi*ep33s, 0, 250*pi*ep33s, 0]
> > [ 0, 250*pi*ep33a, 0, 250*pi*ep33a]
> > [ 250*pi*ep33s, 0, 250*pi*ep33s, 0]
> > [ 0, 250*pi*ep33a, 0, 250*pi*ep33a]
>
> You can't invert this matrix; rows 1 and 3 are identical, as are rows 2 and
> 4. This means it's not full rank and so has no inverse. PINVwon't help
> either -- it's intended for numeric matrices, not symbolic matrices.
>
> If you're trying to invert the matrix in order to solve a system of
> equations, DON'T, repeat DO NOT INVERT IT. Instead use backslash (\) to
> solve the system directly.
>
> --
> Steve Lord
> sl...@mathworks.com
> comp.soft-sys.matlab (CSSM) FAQ:http://matlabwiki.mathworks.com/MATLAB_FAQ

thank u steve. i understand the solution.