weighted fit to log-log data

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Ben
Ben 2014-1-13
评论: Ben 2014-1-15
Hi, I need to perform a first order log-log fit with the ability to weight the samples. This should fit a straight line through data plotted on log-log paper. My code seems right to me but the results are wrong. Can any one set me straight?
x = independand data
y = dependant data
w = weighting scheme
d = lscov( [ones(size(x')) log10(x)'] ,log10(y)',w)
%if i plot this the fit line is out by a factor of ~10^3
loglog(10.^x,10.^y,'o',10.^[.2,.5],10^(d(1)).*10.^([.2,.5]*d(2)),'-')
  1 个评论
Ben
Ben 2014-1-15
Further to this, it seems to me that lscov is correct but my plotting is incorrect. This seems closer, but still incorrect:
loglog(x,y,'o',[.2,.5],10^(d(1))*10.^(d(2)*[.2,.5]),'-')
Any ideas where I'm going wrong?

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