Known Issues for the NAG Library CL Interface

This document reflects all reported and resolved issues that affect recent releases of the NAG Library CL Interface.

Some of these issues may have been fixed at intermediate "point" releases of the Library, while other fixes are scheduled for incorporation at future releases. For library Marks where those fixes are not yet incorporated, a workaround for the known issue is provided wherever possible.

To find the Mark and point release number of your library, call NAG function a00aac( ).

For issues that affect releases of other interfaces, please also see

Order the issues by

c02agc

Synopsis	Overflow may occur if the function attempts to scale the polynomial coefficients.
Description	In rare circumstances overflow may be observed if $scale = Nag_TRUE$ .
Severity	Non-critical
Issue Since Mark	7
Workaround	Set argument $scale = Nag_FALSE$ .

d06acc

Synopsis	d06acc returns $fail . code = NE_MESH_ERROR$ error for some boundary meshes due to an internal scaling issue.
Description	d06acc returns $fail . code = NE_MESH_ERROR$ error for some boundary meshes due to an internal scaling issue.
Severity	Non-critical
Issue Since Mark	7
Fixed at Mark	28.4
Workaround	Scale input boundary mesh prior to calling d06acc so that $= 0$ and $= 1$ .

e01shc

Synopsis	e01shc will occasionally incorrectly identify a point as being outside the region defined by the interpolant.
Description	e01shc will occasionally incorrectly identify a point as being outside the region defined by the interpolant. This leads to the function value being extrapolated rather than interpolated and can lead to incorrect results.
Severity	Non-critical
Issue Since Mark	26.0
Fixed at Mark	27.1
Workaround	None.

e04mtc

Synopsis	$stats$ and $rinfo$ were not correctly filled by the presolver.
Description	The arrays $stats$ and $rinfo$ were not correctly filled when the problem was entirely solved by the presolver. It now returns the correct values. The optional parameter $Print Solution$ now correctly writes the linear constraints dual variables when no bounds are defined on the variables.
Severity	Non-critical
Issue Since Mark	26.1
Fixed at Mark	27
Workaround	Don't rely on $rinfo [0], rinfo [1]$ to hold the primal and dual objective in this case and recompute it as $c^{'} x$ and $b y$ , respectively.

e04mtc

Synopsis	e04mtc does not report the correct solution when $3$ or more columns are proportional to each other in the constraint matrix.
Description	e04mtc does not report the correct solution when $3$ or more columns are proportional to each other in the constraint matrix. In such a case, the solution reported may be infeasible.
Severity	Non-critical
Issue Since Mark	26.1
Fixed at Mark	27
Workaround	A workaround is to disable the more complex presolve operations by setting the optional parameter $LP Presolve = BASIC$ . This may slow down the solver depending on the problem.

e04mtc

Synopsis	In some very rare cases, the solution reported presents big violations on a small number of linear constraints.
Description	In some very rare cases, the solution reported presents big violations on a small number of linear constraints.
Severity	Non-critical
Issue Since Mark	26.1
Fixed at Mark	27.1
Workaround	A workaround is to deactivate the more complex presolver operations with the optional parameter $LP Presolve = BASIC$ .

e04mtc

Synopsis	In some very rare cases, e04mtc reports problem infeasibility for a feasible problem.
Description	In some very rare cases, the solver reports problem infeasibility when there are numerical difficulties.
Severity	Non-critical
Issue Since Mark	26.1
Fixed at Mark	28.6
Workaround	Unfortunately there is no convenient workaround.

e04mtc

Synopsis	In some very rare cases, at presolve phase the solver declares unboundedness on a bounded problem.
Description	In some very rare cases, especially when there are a large amount of singleton variables, the solver might report unbounded error message on a bounded problem.
Severity	Non-critical
Issue Since Mark	26.1
Fixed at Mark	29.0
Workaround	A workaround is to deactivate the more complex presolver operations with the optional parameter $LP Presolve = BASIC$ . This may slow down the solver depending on the problem.

e04mtc

Synopsis	In some cases the solver declares dual infeasibility during presolving for feasible and bounded problems.
Description	For a bounded problem, the solver reports dual infeasibility during dominated columns removal at the presolving stage.
Severity	Non-critical
Issue Since Mark	26.1
Fixed at Mark	29.1
Workaround	A workaround is to deactivate the more complex presolver operations with the optional parameter $LP Presolve = BASIC$ . This may slow down the solver depending on the problem.

e04mtc and e04ptc

Synopsis	Infeasible bounds defined by e04rjc of a variable are ignored and infeasibility is not reported.
Description	When infeasible bounds are defined by e04rjc for a variable, instead of reporting problem infeasibility, the bounds are overridden and wrong solution may be reported.
Severity	Non-critical
Issue Since Mark	26.1
Fixed at Mark	27.1
Workaround	A workaround is to deactivate the more complex presolver operations with the optional parameter $LP Presolve = BASIC$ for e04mtc and $SOCP Presolve = BASIC$ for e04ptc.

e04nrc, e04vkc and e04wec

Synopsis	Optional parameters $List$ and $Nolist$ are not handled correctly.
Description	Functions e04nrc, e04vkc and e04wec do not handle optional parameters $List$ and $Nolist$ correctly. Specifying $List$ does not alter the behaviour of subsequent functions in the suite, and specifying $Nolist$ erroneously reports an error.
Severity	Non-critical
Issue Since Mark	8
Fixed at Mark	27.3
Workaround	Function e04nsc should be used instead to set optional parameters $List$ or $Nolist$ .

e04vhc

Synopsis	Information about the last constraint might not be printed.
Description	If the problem has a nonlinear objective function without a linear part and $objrow < nf$ , the last constraint is not printed in the final information about the solution (Rows section).
Severity	Non-critical
Issue Since Mark	8
Fixed at Mark	26
Workaround	None.

f11bec, f11bsc, f11gec and f11gsc

Synopsis	Multithreaded versions of the functions f11bec, f11bsc, f11gec and f11gsc may produce slightly different results when run on multiple threads.
Description	Multithreaded versions of the functions f11bec, f11bsc, f11gec and f11gsc may produce slightly different results when run on multiple threads, e.g., the number of iterations to solution and the computed matrix norms and termination criteria reported by the associated monitoring functions. A bug affecting f11bec and f11gec has been fixed, and parallel vector dot products have been modified in all functions to improve consistency of results.
Severity	Non-critical
Issue Since Mark	26
Fixed at Mark	27.1
Workaround	None.

f16qec and f16tec

Synopsis	f16qec and f16tec reference diagonal elements when unit diagonal entries are assumed.
Description	f16qec and f16tec reference and copy diagonal elements when unit diagonal entries are assumed.
Severity	Critical
Issue Since Mark	7
Fixed at Mark	28
Workaround	Nothing needs to be done unless diagonal entries of the target matrix contain useful data prior to a call of f16qec or f16tec with $diag = Nag_UnitDiag$ , in which case the useful data should be saved and copied back to the diagonal of the target matrix after the call to either f16qec or f16tec.

f16qfc

Synopsis	f16qfc, if called with $pdb$ that violates minimum contraints, will produce a segmentation fault.
Description	f16qfc, if called with $pdb$ that violates minimum contraints, will produce a segmentation fault.
Severity	Critical
Issue Since Mark	7
Fixed at Mark	28
Workaround	Call f16qfc with $pdb$ that meets the documented minimum contraint.

f16rdc, f16rec, f16udc, f16uec, f16ufc and f16ugc

Synopsis	Incorrect Frobenius norm returned in some cases.
Description	When calling one of the functions: f16rdc, f16rec, f16udc, f16uec, f16ufc and f16ugc with $order = Nag_RowMajor$ and $norm = Nag_FrobeniusNorm$ , the returned norm can be incorrect.
Severity	Critical
Issue Since Mark	23
Fixed at Mark	28
Workaround	These functions will return the correct norm if the $order$ argument is set to $Nag_ColMajor$ and the $uplo$ argument is flipped, i.e., from $Nag_Upper$ to $Nag_Lower$ or vice versa.

f16smc

Synopsis	f16smc returns wrong update of $A$ when $a$ is stored in row major order and $y$ is to be conjugated.
Description	When f16smc is called with $order = Nag_RowMajor$ and $conj = Nag_Conj$ , $A$ is updated as though $conj = Nag_NoConj$ .
Severity	Critical
Issue Since Mark	8
Fixed at Mark	28
Workaround	Call f16smc with $conj = Nag_NoConj$ and conjugate $y$ prior to call.

f16tac

Synopsis	f16tac stops program execution when called with $pda < n$ .
Description	f16tac, when called with $pda < n$ does not return error code $fail . code = NE_INT_2$ , but terminates program execution.
Severity	Critical
Issue Since Mark	8
Fixed at Mark	28
Workaround	Call f16tac with $pda \geq \max (1, n)$ .

f16tfc

Synopsis	f16tfc returns incorrect results when computing a transposed copy of a matrix.
Description	f16tfc returns incorrect results when computing a transposed copy of a matrix.
Severity	Critical
Issue Since Mark	7
Fixed at Mark	28
Workaround	Call f01cwf with $alpha = one$ and $beta = zero$ ; for row-ordered matrices, $m$ and $n$ should be switched.

g02ajc

Synopsis	If the first row or column of the weight matrix $h$ consists only of zeros, then the function will fail to find the nearest correlation matrix for that weight matrix.
Description	An error can occur when the first row or column of the weight matrix $h$ consists only of zeros, then the function will fail to find the nearest correlation matrix for that weight matrix.
Severity	Critical
Issue Since Mark	25
Fixed at Mark	30.1
Workaround	The workaround is to apply a small weight (relative to other non-zero weights given in $h$ ) to one of the elements in the first row/column.

g02cac

Synopsis	When $mean = Nag_AboutZero$ , output arguments $a$ and $a_serr$ are not initialized.
Description	When $mean = Nag_AboutZero$ , output arguments $a$ and $a_serr$ are not initialized. These values relate to a regression constant that is only relevant in the $mean = Nag_AboutMean$ case. However, the code for $mean = Nag_AboutZero$ should initialize them to $0.0$ . This was not done, allowing previously set values or random results to be erroneously returned.
Severity	Non-critical
Issue Since Mark	7
Fixed at Mark	27.3
Workaround	The safest solution is to manually set these to $0.0$ (but only in the $mean = Nag_AboutZero$ case) immediately after calling this function.

g02jfc

Synopsis	A segmentation fault is likely to occur if a model with multiple random statements is supplied to the function, where at least one of those statements does not have a $Subject$ term.
Description	A segmentation fault is likely to occur if a model with multiple random statements is supplied to the function, where at least one of those statements does not have a $Subject$ term. For example, a model specified using: V1 + V2 / SUBJECT = V3 V4 + V5 / SUBJECT = V6 would not trigger the error, but one specified using: V1 + V2 V4 + V5 / SUBJECT = V6 would. The error is not triggered when there is only a single random statement, so a model specified using just V1 + V2 will not trigger the error.
Severity	Critical
Issue Since Mark	27
Fixed at Mark	27.1
Workaround	A workaround to this issue is to always supply a $Subject$ term. If the required model is of the form: V1 + V2 V4 + V5 / SUBJECT = V6 then you can specify an equivalent model by using: V1 + V2 / SUBJECT = DUMMY V4 + V5 / SUBJECT = V6 where the variable DUMMY has a single level, and always takes a value of one. This will require adding the variable DUMMY to your dataset.

Chapter G05

Synopsis	Memory leak reported from CL interface on Windows from checking tools.
Description	A during-execution memory leak can be reported from checking tools on Windows when running a multi-threaded program calling d01xbc.
Severity	Critical
Issue Since Mark	5
Fixed at Mark	28
Workaround	Ignore warnings.

g08ckc and g08clc

Synopsis	The wrong value for $p$ is returned when $aa2$ is large.
Description	In g08ckc and g08clc the value returned for the upper tail probability $p$ is wrong when the calculated Anderson-Darling test statistic $aa2$ is large. In the case of g08ckc, when $aa2 > 153.4677$ the returned value of $p$ should be zero; in the case of g08clc, when $aa2 > 10.03$ the returned value of $p$ should be $\leq \exp (- 14.360135)$ .
Severity	Critical
Issue Since Mark	23
Workaround	Workaround for g08ckc: Call g08ckc(...); If (aa2 > 153.4677) p = 0.0; Workaround for g08clc: Call g08clc(...); If (aa2 > 10.03) p = exp(-14.360135);

g13fac

Synopsis	g13fac may return a negative value as the estimate of the last $β$ parameter (i.e., $β_{p}$ ) for a subset of models.
Description	g13fac can result in a negative value for the estimate of the last $β$ parameter (i.e., $β_{p}$ ) or, if $p = 0$ , the last $α$ parameter (i.e., $α_{q}$ ). This issue only affects a subset of models that have normally distributed errors and do not include an asymmetry term. If the function did not return a negative value as the estimate of the last $β$ parameter (or, if $p = 0$ , the last $α$ parameter), then that particular model was not affected by the issue.
Severity	Critical
Issue Since Mark	7
Fixed at Mark	27
Workaround	None

g22ydc

Synopsis	When $what = Nag_VarianceComponent$ the information returned in $plab$ and/or $vinfo$ may be incorrect.
Description	The information returned in $plab$ and/or $vinfo$ may be incorrect in cases where $what = Nag_VarianceComponent$ and the underlying linear mixed effects regression model has a random variable, with a single level (so either binary or continuous), that only takes the value zero.
Severity	Non-critical
Issue Since Mark	27.0
Workaround	The work around is to drop the term from the model, as it does not contribute. For example, if the random part of your model was specified as: V1 + V2 / SUBJECT=V3 and the variable V2 was a continuous variable, that only takes a value of zero in the data, then this is equivalent to re-specifying the model using: V1 / SUBJECT=V3.

h02dac

Synopsis	In some cases, solver returns inaccurate solution when there are binary variables.
Description	When there are binary variables, the accuracy of the solution will be influenced by the initial values. The solver could return inaccurate solution.
Severity	Non-critical
Issue Since Mark	25
Fixed at Mark	29.1
Workaround	The work around is to use integer variables with $0$ and $1$ as lower and upper bound, respectively.

Metis external package files use large amount of thread local storage (TLS)

Synopsis	Thread Local Storage default limit was exceeded for delay loaded shared library.
Description	A fair amount of thread local storage had been allocated by an auxiliary function which has now been updated to use a very small amount of thread local storage. Prior to the update, this only affected the case where the shared version of the Nag Library was delay loaded, since this assumed a small default maximum amount of thread local storage, which was in fact exceeded. The issue had been present since the introduction of the auxiliary function at Mark 26.1. From Mark 28.6, the amount of thread local storage used is very small and this is no longer an issue.
Severity	Non-critical
Issue Since Mark	26.1
Fixed at Mark	28.6
Workaround	None.