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