Is this the correct way to use MatGetRow? Something wrong here

[Ben Tay]

Hi,

I'm trying to view a particular row of a matrix. This 's what I do in my 
loops:

real(8):: vector(64)

II=36

impl_mat_i=4.

call MatSetValue(A_mat_uv,II,II,impl_mat_i,ADD_VALUES,ierr)

call MatAssemblyBegin(A_mat_uv,MAT_FINAL_ASSEMBLY,ierr)

call MatAssemblyEnd(A_mat_uv,MAT_FINAL_ASSEMBLY,ierr)


call MatGetRow(A_mat_uv,II,PETSC_NULL,PETSC_NULL,vector,ierr)

call MatRestoreRow(A_mat_uv,II,PETSC_NULL,PETSC_NULL,vector,ierr)

When I look at "vector" using visual fortran debugger, I saw many 
different values in it, but I only added 1 value in 1 location. However, 
just before I use MatSetValue, I also called MatGetRow. It was initially 
all zero.

But, if I use call 
MatSetValue(A_mat_uv,II,*1*,impl_mat_i,ADD_VALUES,ierr) instead of II, I 
see only 4 in vector(1).

What happening? Where did all the other values come from? Also, is this 
the best way to view a particular row of a matrix? I tried to use

call MatGetValues(A_mat_uv,1,36,64,1,vector,ierr) to get 1 row of values 
from the 36th row.There are 64 columns in total. Seems like it's the 
wrong way. Can you please show me the correct way?

Thank you.