# File narray_ext.rb, line 141 def stddev(*ranks) if integer? a = self.to_type(NArray::DFLOAT) else a = self end a = NArray.ref(a) n = rank_total(*ranks) if complex? NMath::sqrt( (( a-a.accum(*ranks).div!(n) ).abs**2).sum(*ranks)/(n-1) ) else NMath::sqrt( (( a-a.accum(*ranks).div!(n) )**2).sum(*ranks)/(n-1) ) end end