Re: [Libmesh-devel] svd segfault

[David K. <dav...@ak...>]

On Fri, Jul 29, 2016 at 3:48 PM, John Peterson <jwp...@gm...> wrote:

>
>
> On Fri, Jul 29, 2016 at 12:54 PM, David Knezevic <
> dav...@ak...> wrote:
>
>> Below is a short test case that causes a segfault with DenseMatrix::svd
>> with --enable-complex. I think that the issue is related to the fact that
>> LAPACK clears the "number_val" array, and then it gets cleared again when
>> it goes out of scope. I wasn't able to fix it so far, though (seems like
>> allocating the array with new would do the job, but that didn't seem to
>> work for me), so another pair of eyes on this would be appreciated.
>>
>> This is related to the PR 1042 that I just closed based on comments from
>> John and Roy (I agree that it'd be better to fix this than to require the
>> user to call the SVD themselves).
>>
>
> Thanks for the test case. Note that if you "new" memory and then Lapack
> "free's" it rather than deleting it, I think that's undefined behavior
> (?).  So you might check whether malloc works any better for you.
>


OK, that might be the issue. If so, it should be an easy fix. I'll try that
when I get some time...

David