How can HISAT2/StringTie report decimal coverage values I have performed RNA-seq analysis using HISAT2 &amp; StringTie workflow suggested in: Transcript-level expression analysis of RNA-seq experiments with HISAT, StringTie and Ballgown. 

Some of the transcripts/exons have decimal coverage values (eg., 1.1 or 2.59).  

My question is: How can these tools report decimal coverage? If only half of the read overlaps exon will this exon have 0.5 coverage?
I suspect this is average coverage across the transcript or exon. 

Formula for average coverage:



Where:


N: number of reads mapping/aligning to your transcript/exon
L: average read length
T: Transcript/exon length