logistic 回归Matlab代码
function a alpha = 0.0001; [m,n] = size(q1x); max_iters = 500; X = [ones(size(q1x,1),1), q1x]; % append col of ones for intercept term theta = zeros(n+1, 1); % initialize theta for k = 1:max_iters hx = 1./(1+exp(-X*theta)); theta = theta + alpha * X' * (q1y-hx); ll(k) = sum(q1y .* log(hx) + (1 - q1y) .* log(1 - hx) ); hold on; end plot(q1x(1:50,1),q1x(1:50,2),'o'); hold on; plot(q1x(51:99,1),q1x(51:99,2),'r*'); hold on; x1=0:0.01:8; y=(1-theta(1,1))/theta(3,1)-x1*theta(2,1)/theta(3,1); plot(x1,y)q1x.dat,q1y.dat:http://cs229.stanford.edu/
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