elemental/chat

Jack Poulson

@poulson

was it an intermediate step in an alternating algorithm?

Aidan Dang

@AidanGG

I'm using the svd to cut a matrix into two, then using the svd to cut one of those, and so on

Jack Poulson

@poulson

Aidan Dang

@AidanGG

I'm fairly certain the matrix I have doesn't have any undefineds/NaNs

Jack Poulson

@poulson

it would be good to see if Octave can safely compute the SVD of that matrix as well

my guess is that it would take about 10 minutes

Aidan Dang

@AidanGG

I think scalapack does

Jack Poulson

@poulson

assuming roughly a 3 thousand by 3 thousand matrix

ScaLAPACK uses the QR algorithm

have you tested Elemental's QR algorithm on it?

Aidan Dang

@AidanGG

is that through bidiagSVDctrl.useQR?

Jack Poulson

@poulson

yes, that is the best way

Aidan Dang

@AidanGG

Ok, it still doesn't work

Jack Poulson

@poulson

what is the error/exception?

Aidan Dang

@AidanGG

Did not converge all singular values

Jack Poulson

@poulson

one can increase the maximum number of iterations to see if it was almost converging

Aidan Dang

@AidanGG

Is that qrCtrl.maxIterPerVal?

Jack Poulson

@poulson

bidiagSVDCtrl.qrCtrl.maxIterPerVal = 20 could be tried

yes

Also, did you verify that ScaLAPACK returned with INFO=0?

Aidan Dang

@AidanGG

Oh, I haven't, but the final results were sensible, so I assumed it was ok

https://drive.google.com/open?id=0B3uyvVfsuP46NGhrQzBpdnYyZzg

Jack Poulson

@poulson

I would recommend checking for the sake of consistency, as it could very well be that there is one small troublesome singular value

Aidan Dang

@AidanGG

https://drive.google.com/open?id=0B3uyvVfsuP46RGxTYTNKekhYRmc

Jack Poulson

@poulson

you can also tell Elemental not to worry if the singular values don't all converge

Aidan Dang

@AidanGG

those are my distmatrix.bin and test script

I've tried setting qrctrl.demandconverged to false, but I don't think that worked either

Jack Poulson

@poulson

it still complained about not converging?

I haven't tested that option explicitly but tried to set it up

I'm downloading it now

I have about ten minutes to make/drink coffee, figure this out, and run to work but can hopefully find something

Aidan Dang

@AidanGG

Please don't stress too much about it, you've been a great help.

If I set demandconverged to false, it appears to hang

Jack Poulson

@poulson

something seems to be wrong with that file:

poulson@poulson-ASUS:~/Source/Internal/Elemental/build-gcc$ ./bin/sandbox-test 
terminate called after throwing an instance of 'std::runtime_error'
  what():  Expected file to be 8 bytes but found 63406096

Aborted (core dumped)

how did you create it?

Aidan Dang

@AidanGG

El::Write

I'm on 64 bit ints

Jack Poulson

@poulson

ah, I wonder if that's it

also, have you checked that if you download that .bin file from your Google Drive that you can run your test program with it?

Aidan Dang

@AidanGG

I'll check it out.

Jack Poulson

@poulson

the metadata at the beginning of the file is an El::Int, and that size is variable

I think that is the problem with me trying to run with the 32-bit version

Aidan Dang

@AidanGG

I can get you a version with 32bit ints

after I get some sleep, because it's 3:30am here in Melbourne. Thanks so much for your support.

Jack Poulson

@poulson

no worries, I can build a 64-bit version and debug

get some sleep and I will fix it by tonight

Aidan Dang

@AidanGG

Hello again Jack, my issues with this matrix occur on the default 4 process grid (2x2 after my recent pull) if that is any help.

Jack Poulson

@poulson

does the problem occur on a single process?

Aidan Dang

@AidanGG

mpirun -np 1 appears to work fine, both with useQR true or false.

Aidan Dang

@AidanGG

I've checked with a modified version of the SVD test driver, and the results are good when I run on one process

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