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rINSTCONTROL/@MyExponentialFit/MyExponentialFit.m
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MyExponentialFit.m
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classdef MyExponentialFit < MyFit
properties (Access=public)
%Logical value that determines whether the data should be scaled or
%not
scale_data;
end
%Public methods
methods (Access=public)
%Constructor function
function this=MyExponentialFit(varargin)
this@MyFit(...
'fit_name','Exponential',...
'fit_function','a*exp(b*x)+c',...
'fit_tex','$$ae^{bx}+c$$',...
'fit_params', {'a','b','c'},...
'fit_param_names',{'Amplitude','Rate','Offset'},...
varargin{:});
end
end
methods (Access=protected)
%Overload the doFit function to do scaled fits.
%We here have the choice of whether to scale the data or not.
function doFit(this)
if this.scale_data
ft=fittype(this.fit_function,'coefficients',...
this.fit_params);
opts=fitoptions('Method','NonLinearLeastSquares',...
'Lower',convRealToScaledCoeffs(this,this.lim_lower),...
'Upper',convRealToScaledCoeffs(this,this.lim_upper),...
'StartPoint',convRealToScaledCoeffs(this,this.init_params),...
'MaxFunEvals',2000,...
'MaxIter',2000,...
'TolFun',1e-6,...
'TolX',1e-6);
%Fits with the below properties. Chosen for maximum accuracy.
[this.Fitdata,this.Gof,this.FitInfo]=...
fit(this.Data.scaled_x,this.Data.scaled_y,ft,opts);
%Puts the coeffs into the class variable.
this.coeffs=convScaledToRealCoeffs(this,...
coeffvalues(this.Fitdata));
else
%Do the default fitting if we are not scaling.
doFit@MyFit(this);
end
calcUserParams(this);
end
%Calculates the initial parameters using an external function.
function [init_params,lim_lower,lim_upper]=calcInitParams(this)
if this.scale_data
[init_params,lim_lower,lim_upper]=...
initParamExponential(this.Data.scaled_x,this.Data.scaled_y);
%Convertion back to real values for display.
init_params=convScaledToRealCoeffs(this,init_params);
lim_lower=convScaledToRealCoeffs(this,lim_lower);
lim_upper=convScaledToRealCoeffs(this,lim_upper);
else
[init_params,lim_lower,lim_upper]=...
initParamExponential(this.Data.x,this.Data.y);
end
end
%Function for calculating the parameters shown in the user panel
function calcUserParams(this)
this.tau=abs(1/this.coeffs(2));
this.lw=abs(this.coeffs(2)/pi);
this.Q=pi*this.freq*this.tau;
this.Qf=this.Q*this.freq;
end
function createUserGuiStruct(this)
this.UserGui.Tabs.Q.tab_title='Q';
this.UserGui.Tabs.Q.Children={};
addUserField(this,'Q','tau','\tau (s)',1,...
'enable_flag','off')
addUserField(this,'Q','lw','Linewidth (Hz)',1,...
'enable_flag','off')
addUserField(this,'Q','Q',...
'Qualify Factor (x10^6)',1e6,...
'enable_flag','off','conv_factor',1e6)
addUserField(this,'Q','freq','Frequency (MHz)',1e6,...
'conv_factor',1e6, 'enable_flag','on',...
'Callback',@(~,~) calcUserParams(this));
addUserField(this,'Q','Qf','Q\times f (10^{14} Hz)',1e14,...
'conv_factor',1e14,'enable_flag','off');
addUserField(this,'Q','tag','Tag (number)',1,...
'enable_flag','on')
end
end
methods (Access=private)
%Converts scaled coefficients to real coefficients
function r_c=convScaledToRealCoeffs(this,s_c)
[mean_x,std_x,mean_y,std_y]=calcZScore(this.Data);
r_c(1)=exp(-s_c(2)*mean_x/std_x)*s_c(1)*std_y;
%Edge case for limits
if isnan(r_c(1)); r_c(1)=0; end
r_c(2)=s_c(2)/std_x;
r_c(3)=std_y*s_c(3)+mean_y;
end
function s_c=convRealToScaledCoeffs(this,r_c)
[mean_x,std_x,mean_y,std_y]=calcZScore(this.Data);
s_c(2)=r_c(2)*std_x;
s_c(1)=r_c(1)*exp(s_c(2)*mean_x/std_x)/std_y;
s_c(3)=(r_c(3)-mean_y)/std_y;
end
end
end
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