# [R] How to get the pseudo left inverse of a singular square matrix?

Jerome Asselin jerome at hivnet.ubc.ca
Thu Aug 14 19:29:07 CEST 2003

```No. If B is singular, it's impossible to find a matrix A such that A%*%B
be the identity matrix (unless you can find a number x such that x*0=1).

Cheers,
Jerome

On August 14, 2003 10:02 am, Feng Zhang wrote:
> Thank, Jerome
>
> The question is if this generalized inverse can make
> their product to be identity matrix?
>
>
> ----- Original Message -----
> From: "Jerome Asselin" <jerome at hivnet.ubc.ca>
> To: "Feng Zhang" <f0z6305 at labs.tamu.edu>; "R-Help"
> <r-help at stat.math.ethz.ch>
> Sent: Thursday, August 14, 2003 11:52 AM
> Subject: Re: [R] How to get the pseudo left inverse of a singular square
> matrix?
>
> > Singular matrices are not invertible. However you can calculate the
> > generalized inverse with the function ginv() from package MASS.
> >
> > HTH,
> > Jerome
> >
> > On August 14, 2003 09:24 am, Feng Zhang wrote:
> > > Dear R-listers,
> > >
> > > I have a dxr matrix Z, where d > r.
> > > And the product Z*Z' is a singular square matrix.
> > > The problem is how to get the left inverse U of this
> > > singular matrix Z*Z', such that
> > > U*(Z*Z') = I?
> > >
> > > Is there any to figure it out using matrix decomposition method?
> > >
> > > Thanks a lot for your help.
> > >
> > > Fred
> > >
> > > ______________________________________________
> > > R-help at stat.math.ethz.ch mailing list
> > > https://www.stat.math.ethz.ch/mailman/listinfo/r-help

```