%********************************************************************************************************

% "paramsCal.m" calculates Tconst(ADC or T2) and M0.

% inputs:

% M- The 3D image which was acquired or a set of points.

% x- vector with the 'x' value of the signal (b value or TE, respectively).

% Tconst- The name of the time constant that the user wishs to find: ADC or T2.

% data_type- 3D matrix (=3D) or set of points (=simple).

% outputs:

% M0 - The signal in t=0.

% M0_err- The error in M0.

% TconstVal- The value of the time constant (ADC or T2).

% TconstVal_err- The error in TconstVal. 

% R- The R square measurement.

% xval-  A matrix which describes how mush points were used to compute

% the T. const in each voxel.

%*********************************************************************************************************



function [M0, M0_err, TconstVal, TconstVal_err, R, xval]=paramsCal (M, x, Tconst, data_type, noise)



if strcmp(data_type, 'simple')

    [b,a,b_err,a_err,R]=simple_WLS(M, x, noise);

    xval=0;

else

    [b,a,b_err,a_err,R, xval]=WLS(M, x, noise);

end



if strcmp(Tconst,'ADC')

    TconstVal=-a;

    TconstVal_err=a_err;

elseif strcmp(Tconst,'T2')

    TconstVal=-1./a;

    TconstVal_err=a_err./a.^2;

end



M0=exp(b);

M0_err=M0.*b_err;

end