Home > manopt > core > canGetGradient.m

canGetGradient

PURPOSE ^

Checks whether the gradient can be computed for a problem structure.

SYNOPSIS ^

function candoit = canGetGradient(problem)

DESCRIPTION ^

 Checks whether the gradient can be computed for a problem structure.
 
 function candoit = canGetGradient(problem)

 Returns true if the gradient of the cost function can be computed given
 the problem description, false otherwise.

 See also: canGetCost canGetDirectionalDerivative canGetHessian

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

0001 function candoit = canGetGradient(problem)
0002 % Checks whether the gradient can be computed for a problem structure.
0003 %
0004 % function candoit = canGetGradient(problem)
0005 %
0006 % Returns true if the gradient of the cost function can be computed given
0007 % the problem description, false otherwise.
0008 %
0009 % See also: canGetCost canGetDirectionalDerivative canGetHessian
0010 
0011 % This file is part of Manopt: www.manopt.org.
0012 % Original author: Nicolas Boumal, Dec. 30, 2012.
0013 % Contributors:
0014 % Change log:
0015 %
0016 %   June 28, 2016 (NB):
0017 %       Added support for getPartialGradient
0018 %
0019 %   Nov. 1, 2016 (NB):
0020 %       Added support for gradient from directional derivatives
0021 
0022     candoit = isfield(problem, 'grad') || isfield(problem, 'costgrad') || ...
0023               canGetEuclideanGradient(problem) || ...
0024               canGetPartialGradient(problem) || ...
0025               ... % Check if directional derivatives can be obtained, since
0026               ... % it is possible to compute the gradient from directional
0027               ... % derivatives (expensively). Here, it is not possible to
0028               ... % call canGetDirectionalDerivative, because that function
0029               ... % would then potentially call canGetGradient, thus 
0030               ... % starting an infinite loop. As a result, we have some
0031               ... % code redundancy: the check below needs to be kept
0032               ... % equivalent to the check in canGetDirectionalDerivative.
0033               isfield(problem, 'diff');
0034     
0035 end

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