44 lines
923 B
Matlab
44 lines
923 B
Matlab
clear
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close all
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load('lin_regression.mat')
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ms = -1:0.5:5;
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ns = -10:1:10;
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position = [-2. 10.];
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gradient = [];
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error = [];
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eps = 0.01;
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% claculate error surface
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error_surf = zeros(length(ms), length(ns));
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for i = 1:length(ms)
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for j = 1:length(ns)
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error_surf(i,j) = lsqError([ms(i), ns(j)], x, y);
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end
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end
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figure()
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hold on
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[N, M] = meshgrid(ns, ms);
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surface(M,N, error_surf, 'FaceAlpha', 0.5);
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view(3)
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xlabel('slope')
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ylabel('intersection')
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zlabel('error')
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% do the descent
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while isempty(gradient) || norm(gradient) > 0.1
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gradient = lsqGradient(position, x,y);
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error = lsqError(position, x, y);
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plot3(position(1), position(2), error, '.', 'color', 'red', 'markersize', 20)
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position = position - eps .* gradient;
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pause(0.05)
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end
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grid on
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set(gcf, 'paperunits', 'centimeters', 'papersize', [15, 15], ...
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'paperposition', [0., 0., 15, 15])
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saveas(gcf, 'gradient_descent', 'pdf')
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