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### [Lapack] matrix splitting problem with dstebz and sstebz

 ``` Hello Phil, Thanks for the bug report. I have added your bug report to the LAPACK Errata file. See: http://www.netlib.org/lapack/Errata/ , bug0032. We will try to have a look at some points. Best wishes, Julien On Mon, 29 Jun 2009, Phil DeMier wrote: `````` Greetings, We have discovered a problem with DSYEVX. The problem occurs for certain matrices created using a specific algorithm. We are able to work around the problem by removing the "matrix splitting" code in dstebz. This problem also occurs in sstebz. DO 10 J = 2, N TMP1 = E( J-1 )**2 !! IF( ABS( D( J )*D( J-1 ) )*ULP**2+SAFEMN.GT.TMP1 ) THEN !! ISPLIT( NSPLIT ) = J - 1 !! NSPLIT = NSPLIT + 1 !! WORK( J-1 ) = ZERO !! ELSE WORK( J-1 ) = TMP1 PIVMIN = MAX( PIVMIN, TMP1 ) !! END IF 10 CONTINUE Please see the attached test program testevx.f which demonstrates the failure. (See attached file: testevx.f) Output from the test: *** Math check results for DSYT22 with N= 7 and M= 5 *** exceeded the threshold value of .10000000D+03 *** Math check: | U' A U - S | / ( |A| m ulp ) *** result was .76390963D+13 *** Math check: | I - U'U | / ( m ulp ) *** result was .15278193D+15 `````` ```
 Current Thread [Lapack] matrix splitting problem with dstebz and sstebz, Phil DeMier [Lapack] matrix splitting problem with dstebz and sstebz, Julien Langou <=

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