Re: [Mplapack-devel] possibly a bug in Cheev

[Maho N. <ma...@ri...>]

Hi Saitoh-san

Please apply following patch.

$ diff -u mlapack/reference/Rlaev2.cpp~ mlapack/reference/Rlaev2.cpp
--- Rlaev2.cpp~ 2012-08-09 14:56:17.156927491 +0900
+++ Rlaev2.cpp  2012-08-09 18:37:00.635038092 +0900
@@ -142,8 +142,6 @@
            *cs1 = one;
            *sn1 = zero;
        } else {
-           printf("#Rlaev2 Checkpoint 13 Not checked\n");
-           exit(1);
            tn = -cs / tb;
            *cs1 = one / sqrt(one + tn * tn);
            *sn1 = tn * (*cs1);

This should work.

Thanks
 Nakata Maho

From: Akira SaiToh <aki...@ni...>
Subject: Re: [Mplapack-devel] possibly a bug in Cheev
Date: Thu, 09 Aug 2012 14:25:35 +0900

> Dear Nakata-san,
> 
> Thanks for your suggestion.
> Indeed, the matrix in the previous email was a singular matrix.
> But sometimes Cheev fails to find eigenvalues also for a small
> non-singular Hermitian matrix. A typical example is
> 
> 2 0 1
> 0 2 0
> 1 0 2
> 
> Its eigenvalues are 1, 2, and 3. For this matrix, Cheev stops
> together with the message "#Rlaev2 Checkpoint 13 Not checked"
> as is similar to the previous example.
> 
> I am not sure if this phenomenon is dependent on a system
> environment. Could somebody test Cheev with the above matrix?
> 
> Thank you for your attentions.
> Regards,
> Akira SaiToh
> 
> 2012-08-09 10:22 Maho NAKATA wrote:
>> Akira SaiTohさま
>>
>> すいません、遅くなって。
>> まだ解決してませんでしょうか。
>>
>> singularじゃなさそうな行列を適当に入れてみたら
>> 如何でしょうか。
>> thanks
>