Does the scipy's logsumexp() implementation include the hack that prevents underflow by subtracting the maximum found value in the array from each element?
The one explained here below, where m = maxval:
You can inspect the source code defining logsumexp here. (Note that there is a link to the source on the doc page).
You'll see:
a_max = a.max(axis=0)
...
out = log(sum(exp(a - a_max), axis=0))
So yes, scipy's logsumexp is subtracting the maximum from each element.
来源：https://stackoverflow.com/questions/25651480/does-scipy-logsumexp-deal-with-the-underflow-challenge