canGetSqrtPrecon

 Checks whether a square root of preconditioner was specified in problem.

 function candoit = canGetSqrtPrecon(problem)

 Returns true if the problem structure allows for applying the square root
 of a preconditioner to tangent vectors at a given point. The square root
 of the preconditioner at x must be a symmetric, positive definite
 operator Q such that applying Q twice (Q o Q) amounts to applying the
 preconditioner once. If both a preconditioner and a square root of
 preconditioner are provided, it is the user's responsibility to ensure
 their compatibility.

 Similarly to getPrecon, if the present function returns false, calls to
 getSqrtPrecon will still work: they will act as the identity. Note that
 this may be incompatible with the preconditioner if it is given. Thus,
 always check by calling canGetSqrtPrecon first.

 See also: canGetPrecon getSqrtPrecon getPrecon

0001 function candoit = canGetSqrtPrecon(problem)
0002 % Checks whether a square root of preconditioner was specified in problem.
0003 %
0004 % function candoit = canGetSqrtPrecon(problem)
0005 %
0006 % Returns true if the problem structure allows for applying the square root
0007 % of a preconditioner to tangent vectors at a given point. The square root
0008 % of the preconditioner at x must be a symmetric, positive definite
0009 % operator Q such that applying Q twice (Q o Q) amounts to applying the
0010 % preconditioner once. If both a preconditioner and a square root of
0011 % preconditioner are provided, it is the user's responsibility to ensure
0012 % their compatibility.
0013 %
0014 % Similarly to getPrecon, if the present function returns false, calls to
0015 % getSqrtPrecon will still work: they will act as the identity. Note that
0016 % this may be incompatible with the preconditioner if it is given. Thus,
0017 % always check by calling canGetSqrtPrecon first.
0018 %
0019 % See also: canGetPrecon getSqrtPrecon getPrecon
0020 
0021 % This file is part of Manopt: www.manopt.org.
0022 % Original author: Nicolas Boumal, April 3, 2015.
0023 % Contributors:
0024 % Change log:
0025 
0026     candoit = isfield(problem, 'sqrtprecon');
0027     
0028 end