EMSC_test.m

%% EMSC_test - Generate synthetic scatter-affected spectra for EMSC.
% Creates spectra with multiplicative scatter, polynomial baseline effects,
% and measurement noise around a known reference spectrum.
% Use as demo data for the EMSC GUI.
%
% Output variables:
%   spectra   - 30x600 matrix (samples x wavelengths)
%   wavelength - 1x600 vector (nm)
%   reference - 1x600 known reference spectrum for custom-reference mode
%
% Author: Lovelace's Square
% Date Created: 2026-07-20
% License: MIT
% Reviewed by Lovelace's Square: Yes
% Version: v 1.0

rng(42);

nSamples = 30;
nChannels = 600;
wavelength = linspace(1000, 2400, nChannels);
x = linspace(-1, 1, nChannels);

gauss = @(center, height, width) height .* ...
    exp(-0.5 .* ((wavelength - center) ./ width).^2);

% Known spectrum used to create and validate the synthetic samples.
reference = 0.35 + ...
    gauss(1120, 0.65, 45) + ...
    gauss(1380, 0.95, 65) + ...
    gauss(1700, 0.75, 50) + ...
    gauss(1980, 1.10, 70) + ...
    gauss(2220, 0.80, 55);

spectra = zeros(nSamples, nChannels);

for s = 1:nSamples
    multiplier = 0.70 + 0.60 * rand();
    baseline = (0.04 * randn()) + ...
        (0.10 * randn()) .* x + ...
        (0.06 * randn()) .* x.^2;
    noise = 0.018 * randn(1, nChannels);

    spectra(s, :) = multiplier .* reference + baseline + noise;
end

clearvars -except spectra wavelength reference

fprintf('Created: spectra (%dx%d), wavelength (1x%d), reference (1x%d)\n', ...
    size(spectra, 1), size(spectra, 2), length(wavelength), length(reference));
fprintf('Contains multiplicative scatter, polynomial baseline effects, and noise.\n');
fprintf('Run EMSC(spectra) and select reference as a custom reference if needed.\n');