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clearall;clc%Byassumingthesampledataisundertheweibull3distribution,togetthe3parameters,%aispostitionparameter,bisscaleparameter,cisshapeparametersample=[31.834.432.632.732.432.831.332.234.231.229.730.230.933.631.232.230.632.133.933.5]S=sort(sample);num=length(sample);pwm(1)=mean(S);forj=1:num-1b=0;fori=1:numifnum-i=ja=prod(1:num-i)/prod(1:j)/prod(1:num-i-j);elsea=0;endb=b+a*S(i);endb=b/num;b=b*prod(1:j)*prod(1:num-j-1)/prod(1:num-1);pwm(j+1)=b;enda=4*(pwm(4)*pwm(1)-pwm(2)*pwm(2))/(4*pwm(4)+pwm(1)-4*pwm(2))b=(pwm(1)-a)/gamma(log((pwm(1)-2*pwm(2))/(pwm(2)-2*pwm(4)))/log(2))c=log(2)/log((pwm(1)-2*pwm(2))/(2*(pwm(2)-2*pwm(4))))