how do you access the nonzero elements in SeqAIJ matrices

[Barry Smith]

   Looks fine to me. I removed the gratuitous C++ and changed
#include <private/matimpl.h> to
#include <src/mat/impls/aij/seq/aij.h>

   Do the PETSc examples work?

    Barry


anlext2wls165:ksp/examples/tutorials] bsmith% ./ex1 -mat_view |& more
row 0: (1, 0.1)  (5, 0.5)  (7, 0.7)
row 1: (3, 1.1)  (4, 1.2)
row 2: (1, 1.7)  (3, 1.9)  (6, 2.2)
row 3: (2, 2.6)  (5, 2.9)  (7, 3.1)
row 4: (3, 3.5)  (5, 3.7)
row 5: (0, 4)  (4, 4.4)  (6, 4.6)
row 6: (1, 4.9)  (5, 5.3)  (7, 5.5)
row 7: (3, 5.9)  (5, 6.1)
ptr[0] = 0
ptr[1] = 3
ptr[2] = 5
ptr[3] = 8
ptr[4] = 11
ptr[5] = 13
ptr[6] = 16
ptr[7] = 19
ind[0] = 1
ind[1] = 5
ind[2] = 7
ind[3] = 3
ind[4] = 4
ind[5] = 1
ind[6] = 3
ind[7] = 6
ind[8] = 2
ind[9] = 5
ind[10] = 7
ind[11] = 3
ind[12] = 5
ind[13] = 0
ind[14] = 4
ind[15] = 6
ind[16] = 1
ind[17] = 5
ind[18] = 7
ind[19] = 3
ind[20] = 5
val[0]] = 0.100000
val[1]] = 0.500000
val[2]] = 0.700000
val[3]] = 1.100000
val[4]] = 1.200000
val[5]] = 1.700000
val[6]] = 1.900000
val[7]] = 2.200000
val[8]] = 2.600000
val[9]] = 2.900000
val[10]] = 3.100000
val[11]] = 3.500000
val[12]] = 3.700000
val[13]] = 4.000000
val[14]] = 4.400000
val[15]] = 4.600000
val[16]] = 4.900000
val[17]] = 5.300000
val[18]] = 5.500000
val[19]] = 5.900000
val[20]] = 6.100000


On Aug 4, 2008, at 12:55 PM, Ahmed El Zein wrote:

> On Mon, 2008-08-04 at 11:14 -0500, Barry Smith wrote:
>> Send us the code. This is suppose to be easy stuff.
>>
> I have attached the code.
>
> Ahmed
>>    Barry
>>
>> On Aug 4, 2008, at 11:09 AM, Ahmed El Zein wrote:
>>
>>> On Mon, 2008-08-04 at 23:13 +0800, Zi-Hao Wei wrote:
>>>> On Mon, Aug 4, 2008 at 10:53 PM, Ahmed El Zein <ahmed at azein.com>
>>>> wrote:
>>>>> my code looks like:
>>>>>  ierr = MatCreate(PETSC_COMM_WORLD,&A); CHKERRQ(ierr);
>>>>>  ierr = MatSetSizes(A,M,N,M,N); CHKERRQ(ierr);
>>>>>  ierr = MatSetType(A, MATSEQAIJ); CHKERRQ(ierr);
>>>>>  ierr =  MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY); CHKERRQ(ierr);
>>>>>  [...lots of MatSetValue() calls...]
>>>>>  ierr = MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY); CHKERRQ(ierr);
>>>>
>>>> I think that the code should be
>>>> ierr = MatCreate(PETSC_COMM_WORLD,&A); CHKERRQ(ierr);
>>>> ierr = MatSetSizes(A,M,N,M,N); CHKERRQ(ierr);
>>>> ierr = MatSetType(A, MATSEQAIJ); CHKERRQ(ierr);
>>>> [...lots of MatSetValue() calls...]
>>>> ierr = MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY); CHKERRQ(ierr);
>>>> ierr = MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY); CHKERRQ(ierr);
>>>>
>>>> The routines MatAssemblyBegin and MatAssemblyEnd should be called
>>>> after completing all calls to MatSetValues().
>>> You are right of course. But if these 2 calls are meant to be right
>>> after each other, why isn't there just one MatAssembly() call  
>>> versus a
>>> Begin and End call?
>>>
>>> btw fixing this did not affect the problem I had.
>>>
>>> Ahmed
>>>
> <petsc.cpp>