[petsc-users] Coloring of -mat_view draw

[Matthew Knepley]

On Mon, Sep 5, 2016 at 4:31 AM, Dave May <dave.mayhem23 at gmail.com> wrote:

> On 5 September 2016 at 10:43, Justin Chang <jychang48 at gmail.com> wrote:
>
>> Hi all,
>>
>> So i used the following command-line options to view the non-zero
>> structure of my assembled matrix:
>>
>> -mat_view draw -draw_pause -1
>>
>> And I got an image filled with cyan squares and dots. However, if I
>> right-click on the image a couple times, I now get cyan, blue, and red
>> squares. What do the different colors mean?
>>
>
> Red represents positive numbers.
> Blue represents negative numbers.
>
> I believe cyan represents allocated non-zero entries which were never
> populated with entries (explicit zeroes). Someone will correct me if I am
> wrong here regarding cyan...
>

When DMMatrix() is called, it first preallocates a matrix, then fills it
with zeros and assembles. This is the cyan matrix. Then
you fillit with nonzeros. This is the second picture with red and blue.
There is an option for turning off the zero filling.

  Matt


> Thanks,
>   Dave
>
>
>> Attached are the images of the two cases:
>>
>> Thanks,
>> Justin
>>
>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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