calcExternalForcesPeriodicity.m

% This function is part of the NMSM Pipeline, see file for full license.
%
% This function calculates the difference between the starting and final
% external force (ground reaction forces for now) for the specified foot
% and force. 
%
% (Cell, struct, Array of string) -> (Number)
% 


function externalForcesPeriodicity = calcExternalForcesPeriodicity( ...
    groundReactionForces, contactSurfaces, forceName)
for i = 1:length(contactSurfaces)
    indx = find(strcmp(convertCharsToStrings( ...
        contactSurfaces{i}.forceColumns), forceName));
    if ~isempty(indx)
        externalForcesPeriodicity = diff(groundReactionForces{i}(:, indx));
    end
end
end