Fix integer overflow in LAPACK DBDSQR, SBDSQR (#1135)
* Fix integer overflow in DBDSQR As noted in lapack issue 135, an integer overflow in the calculation of the iteration limit could lead to an immediate return without any iterations having been performed if the input matrix is sufficiently big. * Fix integer overflow in SBDSQR As noted in lapack issue 135, an integer overflow in the calculation of the iteration limit could lead to an immediate return without any iterations having been performed if the input matrix is sufficiently big. * Fix integer overflow in threshold calculation Related to lapack issue 135, the threshold calculation can overflow as well as the multiplication is evaluated from left to right. Without explicit parentheses, the calculation would overflow for N >= 18919 * Fix integer overflow in threshold calculation Related to lapack issue 135, the threshold calculation can overflow as well as the multiplication is evaluated from left to right. Without explicit parentheses, the calculation would overflow for N >= 18919
This commit is contained in:
Martin Kroeker
GitHub
parent
66dc10b019
commit
7908efafc8
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@ -214,6 +214,16 @@
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*> through the inner loop exceeds MAXITR*N**2.
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*> \endverbatim
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*
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*> \par Note:
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* ===========
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*>
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*> \verbatim
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*> Bug report from Cezary Dendek.
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*> On March 23rd 2017, the INTEGER variable MAXIT = MAXITR*N**2 is
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*> removed since it can overflow pretty easily (for N larger or equal
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*> than 18,919). We instead use MAXITDIVN = MAXITR*N.
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*> \endverbatim
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*
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* Authors:
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* ========
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*
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@ -266,8 +276,8 @@
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* ..
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* .. Local Scalars ..
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LOGICAL LOWER, ROTATE
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INTEGER I, IDIR, ISUB, ITER, J, LL, LLL, M, MAXIT, NM1,
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$ NM12, NM13, OLDLL, OLDM
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INTEGER I, IDIR, ISUB, ITER, ITERDIVN, J, LL, LLL, M,
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$ MAXITDIVN, NM1, NM12, NM13, OLDLL, OLDM
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DOUBLE PRECISION ABSE, ABSS, COSL, COSR, CS, EPS, F, G, H, MU,
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$ OLDCS, OLDSN, R, SHIFT, SIGMN, SIGMX, SINL,
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$ SINR, SLL, SMAX, SMIN, SMINL, SMINOA,
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@ -400,20 +410,21 @@
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40 CONTINUE
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50 CONTINUE
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SMINOA = SMINOA / SQRT( DBLE( N ) )
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THRESH = MAX( TOL*SMINOA, MAXITR*N*N*UNFL )
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THRESH = MAX( TOL*SMINOA, MAXITR*(N*(N*UNFL)) )
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ELSE
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*
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* Absolute accuracy desired
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*
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THRESH = MAX( ABS( TOL )*SMAX, MAXITR*N*N*UNFL )
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THRESH = MAX( ABS( TOL )*SMAX, MAXITR*(N*(N*UNFL)) )
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END IF
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*
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* Prepare for main iteration loop for the singular values
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* (MAXIT is the maximum number of passes through the inner
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* loop permitted before nonconvergence signalled.)
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*
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MAXIT = MAXITR*N*N
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ITER = 0
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MAXITDIVN = MAXITR*N
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ITERDIVN = 0
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ITER = -1
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OLDLL = -1
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OLDM = -1
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*
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@ -429,8 +440,13 @@
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*
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IF( M.LE.1 )
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$ GO TO 160
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IF( ITER.GT.MAXIT )
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*
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IF( ITER.GE.N ) THEN
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ITER = ITER - N
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ITERDIVN = ITERDIVN + 1
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IF (ITERDIVN.GE.MAXITDIVN )
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$ GO TO 200
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END IF
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*
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* Find diagonal block of matrix to work on
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*
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@ -214,6 +214,16 @@
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*> through the inner loop exceeds MAXITR*N**2.
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*> \endverbatim
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*
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*> \par Note:
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* ===========
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*>
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*> \verbatim
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*> Bug report from Cezary Dendek.
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*> On March 23rd 2017, the INTEGER variable MAXIT = MAXITR*N**2 is
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*> removed since it can overflow pretty easily (for N larger or equal
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*> than 18,919). We instead use MAXITDIVN = MAXITR*N.
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*> \endverbatim
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*
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* Authors:
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* ========
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*
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@ -266,8 +276,8 @@
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* ..
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* .. Local Scalars ..
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LOGICAL LOWER, ROTATE
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INTEGER I, IDIR, ISUB, ITER, J, LL, LLL, M, MAXIT, NM1,
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$ NM12, NM13, OLDLL, OLDM
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INTEGER I, IDIR, ISUB, ITER, ITERDIVN J, LL, LLL, M,
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$ MAXITDIVN, NM1, NM12, NM13, OLDLL, OLDM
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REAL ABSE, ABSS, COSL, COSR, CS, EPS, F, G, H, MU,
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$ OLDCS, OLDSN, R, SHIFT, SIGMN, SIGMX, SINL,
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$ SINR, SLL, SMAX, SMIN, SMINL, SMINOA,
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@ -400,20 +410,21 @@
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40 CONTINUE
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50 CONTINUE
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SMINOA = SMINOA / SQRT( REAL( N ) )
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THRESH = MAX( TOL*SMINOA, MAXITR*N*N*UNFL )
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THRESH = MAX( TOL*SMINOA, MAXITR*(N*(N*UNFL)) )
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ELSE
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*
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* Absolute accuracy desired
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*
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THRESH = MAX( ABS( TOL )*SMAX, MAXITR*N*N*UNFL )
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THRESH = MAX( ABS( TOL )*SMAX, MAXITR*(N*(N*UNFL)) )
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END IF
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*
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* Prepare for main iteration loop for the singular values
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* (MAXIT is the maximum number of passes through the inner
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* loop permitted before nonconvergence signalled.)
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*
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MAXIT = MAXITR*N*N
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ITER = 0
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MAXITDIVN = MAXITR*N
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ITERDIVN = 0
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ITER = -1
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OLDLL = -1
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OLDM = -1
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*
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@ -429,8 +440,13 @@
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*
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IF( M.LE.1 )
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$ GO TO 160
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IF( ITER.GT.MAXIT )
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*
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IF( ITER.GE.N ) THEN
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ITER = ITER - N
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ITERDIVN = ITERDIVN + 1
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IF( ITERDIVN.GE.MAXITDIVN )
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$ GO TO 200
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END IF
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*
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* Find diagonal block of matrix to work on
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*
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