createSurrogateModel.m

% This function is part of the NMSM Pipeline, see file for full license.
%
% This function fits muscle tendon lengths and moment arms as a 
% function of joint angles for all muscles
%
% Inputs:
% jointAngles (numberFrames x degreesOfFreedom)
% muscleTendonLengths (numberFrames x 1)
% momentArms (numberFrames x degreesOfFreedom)
% polynomialDegree (value)
%
% (2D Number matrix, Number array, 2D Number matrix, Number) -> 
% (Symbol array, 2D Symbol array, Number array)
%
% returns polynomial expressions with corresponding coefficients that
% best fit experimental muscle tendon lengths and moment arms for all 
% muscles.

% -----------------------------------------------------------------------

function [polynomialExpressionMuscleTendonLengths, ...
    polynomialExpressionMuscleTendonVelocities, ...
    polynomialExpressionMomentArms, coefficients] = ...
    createSurrogateModel(jointAngles, muscleTendonLengths, ...
    momentArms, polynomialDegree)

% Create surorogate model for all muscles
for i = 1 : size(muscleTendonLengths, 2)
[polynomialExpressionMuscleTendonLengths{i}, ... 
    polynomialExpressionMuscleTendonVelocities{i}, ...
    polynomialExpressionMomentArms{i}, coefficients{i}] = ...
    createMuscleSpecificSurrogateModel(jointAngles{i}, ...
    muscleTendonLengths(:, i), momentArms{i}, polynomialDegree);
end
end