function [fitresult, gof] = createFit(SQRT_tsat, SDTD)
%CREATEFIT(SQRT_TSAT,SDTD)
%  Create a fit.
%
%  Data for 'SDTD_fit' fit:
%      X Input : SQRT_tsat
%      Y Output: SDTD
%  Output:
%      fitresult : a fit object representing the fit.
%      gof : structure with goodness-of fit info.
%
%  See also FIT, CFIT, SFIT.

%  Auto-generated by MATLAB on 06-May-2020 16:15:54

% export data
fname = '/Users/jcmunoz/Documents/UEA/test_SDTD_fit_Matlab.xlsx';
data = readmatrix(fname);
SQRT_tsat = data(:,1);
SDTD = data(:,2);
scatter(SQRT_tsat,SDTD);

%% Fit: 'untitled fit 1'.
[xData, yData] = prepareCurveData( SQRT_tsat, SDTD );

% Set up fittype and options.
ft = fittype( 'C*erfc(r/(sqrt(4*D*x))-b)', 'independent', 'x', 'dependent', 'y' );
opts = fitoptions( 'Method', 'NonlinearLeastSquares' );
opts.Display = 'Off';
opts.Lower = [-Inf 0 1 0.2];
opts.StartPoint = [1 0.00012 1 0.2];
opts.Upper = [Inf 0.1 1 0.2];

% Fit model to data.
[fitresult, gof] = fit( xData, yData, ft, opts );

% Plot fit with data.
figure( 'Name', 'SDTD_fit' );
h = plot( fitresult, xData, yData );
legend( h, 'SDTD vs. SQRT_tsat', 'SDTD_fit', 'Location', 'NorthEast', 'Interpreter', 'none' );
% Label axes
xlabel( 'SQRT_tsat', 'Interpreter', 'none' );
ylabel( 'SDTD', 'Interpreter', 'none' );
grid on