%CONESPECTRA  Read and write conespectra.
%
% Thorsten Hansen 2008-05-13

% read data
[wavelength L M S] = textread('cones.txt', '%d%f%f%f','delimiter', ',');

% alternatively, use dlmread
% data = dlmread('cones.txt', ',')
% wavelength = data(:,1); L = data(:,2); M = data(:,3); S = data(:,4);

% alternatively, read directly from web 
%url = 'http://www.allpsych.uni-giessen.de/vf/SS-2008-matlab-programmierung-graduiertenkolleg/blatt2/cones.txt';
%data = urlread(url);
%[wavelength L M S] = strread(data, '%d%f%f%f','delimiter', ','); 



% plot
plot(wavelength, S, wavelength, M, wavelength, L)
xlabel('Wavelength (nm)')
ylabel('Spectral sensitivity')
box off


% myvlambda
LplusM = L + M;
LplusM = LplusM/max(LplusM(:)); % normalize 
dlmwrite('myvlambda.txt', [wavelength LplusM], ',')


% read and plot
V = dlmread('myvlambda.txt', ',');
plot(V(:, 1), V(:, 2))
box off
xlabel('Wavelength (nm)')
ylabel('Spectral sensitivity')

% plot LplusM on top to compare visually...
hold on 
plot(wavelength, LplusM, 'r--')

% compare numerically 
max(LplusM - V(:,2))

% improve: save as matfile
myvlambda = LplusM;
save myvlambda myvlambda
clear myvlambda
whos myvlambda % gone, ok

load myvlambda
max(LplusM - myvlambda)