4 ms·
abs(x) = sqrt(x*x), no?
by traes 6mo ago
abs(x) = sqrt(x*x), no?
- throwaway81523 6mo agoI think the issue might be the branch cut in the sqrt function. Per the wiki article, elementary functions have to be differentiable in the complex plane at all but a finite number of points.
- gus_massa 6mo agoThe origianl article use complex numbers, in particular to get sin and cos from eml: > e^{iφ} = cosφ + i sin φ So x may be a complex number and sqrt(x*x) is a complex number that sometimes is equal to x and sometimes to -x depending on how lucky you were selecting the branches of sqrt.