The apparatus 15 wherein {HEAD ~ said calculating means} comprises {TAIL ~ operational amplifiers} configured in such a way as to calculate said first voltage and said corrected current 
The apparatus 15 wherein { HEAD ~ said calculating means } comprises { TAIL ~ operational amplifiers } configured in such a way as to calculate said first voltage and said corrected current
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH