Hi, Thanks Hong and Matt. So looks like I don't have to call MatSetValues() since I specify the row, column indices and the values corresponding to it when I use MatCreateMPIIJWithArrays()?
Cheers, Dominic -----Original Message----- From: [email protected] [mailto:owner-petsc-users at mcs.anl.gov] On Behalf Of Hong Zhang Sent: Wednesday, January 31, 2007 11:57 PM To: petsc-users at mcs.anl.gov Subject: Re: Reading a Sparse matrix in CRS format from a function to be used in parallel linear solvers Dominic, You may use MatCreateMPIIJWithArrays() to achieve this. Hong On Wed, 31 Jan 2007, Matthew Knepley wrote: > On 1/31/07, #DOMINIC DENVER JOHN CHANDAR# <DOMI0002 at ntu.edu.sg> wrote: > > > > Hi, > > > > I have a function which creates a sparse matrix following a > > certain eqn and returns a pointer to the row, column index and the > > value of a sparse matrix (CRS- form). > > i j val > > 1 1 1.0 > > 2 2 1.0 > > 2 3 -1.5.. > > so on... > > > > The matrix *may not **have a definite pattern* like the one we see > > for tridiagonal or pentadiagonal matrices or the test cases (linear > > solvers) cited in the petsc documentation. Now, i would like to use > > the linear solvers in petsc to solve the system of equations. I do > > not want to write that sparse matrix into a file and read it into > > petsc since it may be huge.I would like to call that function from > > petsc and would return the pointer to i j and val and insert values > > of this sparse matrix using MatSetValues in parallel. How can I achieve this ? > > > > We do not have CRS format as it is not a very space efficient format. > Most of our formats are row-oriented. I suggest looking at the example > for MatSetValues() and trying to rework the discretization function to > directly call this. Most discretizations naturally generate row-by-row > values or even blocks like FEM. Even totally nustructured stuff from > economics is row-by-row. > > Thanks, > > Matt > > Cheers, > > Dominic > > > -- > One trouble is that despite this system, anyone who reads journals > widely and critically is forced to realize that there are scarcely any > bars to eventual publication. There seems to be no study too > fragmented, no hypothesis too trivial, no literature citation too > biased or too egotistical, no design too warped, no methodology too > bungled, no presentation of results too inaccurate, too obscure, and > too contradictory, no analysis too self-serving, no argument too > circular, no conclusions too trifling or too unjustified, and no > grammar and syntax too offensive for a paper to end up in print. -- > Drummond Rennie >
