%%% type/paste these into MATLAB prompt

%%% plot exponential decay curves for two different T2's on one graph
hold;                                  % put multiple plots on one graph
T2short = 30;
T2long = 60;
step = 0.1;
t = 0:step:250;
sigshort = exp(-t/T2short);
siglong = exp(-t/T2long);
plot(t,sigshort,'r');
plot(t,siglong,'g');

%%% plot signal eq. for FLASH sequence as function of flip angle 0-90 deg
hold;
T1 = 1100;
T2 = 90;
PD = 0.68;
TR = 19;
TE =  6;
step = 0.02;
flip = 0:step:pi/2;
numer = PD*(1 - exp(-TR/T1));
denom = 1 - cos(flip)*exp(-TR/T1);
numer2 = sin(flip)*exp(-TE/T2);
sig = numer ./ denom .* numer2;        % dots means component-wise operation
plot(flip,sig,'g');

%%% plot image and its amplitude spectrum (k-space amplitude) on one page
[get any tiff, e.g., http://www.cogsci.ucsd.edu/~sereno/276/t1sag.tiff]
figure;                                % this is a comment
Im = double(imread('t1sag.tiff'));     % load a tiff into a matrix
FT = fftshift(fft2(Im));               % take the Fourier transform of it
FT_Amp = abs(FT);                      % extract Fourier amplitude
minAmp = min(min(FT_Amp));
maxAmp = max(max(FT_Amp)); 
colormap gray; 
subplot(1,2,1);
imagesc(Im);                           % auto scale, display image
axis square;
title('Real Image'); 
subplot(1,2,2);
imagesc(FT_Amp,[minAmp 0.01*maxAmp]);  % change scale for better visibility
axis square;
title('K-Space Ampl');