SONFEqual

  Tests a filter mask structure for active layers

  Implemented through SONFEqual.dll

  ANS=SONFEQUAL(FILTERMASK)

  Sets bits 1 to 4 in the output if layers 1 to 4 of the filter mask
  do anything i.e. have cleared bits

  Author:Malcolm Lidierth
  Matlab SON library:
  Copyright © The Author & King's College London 2005-2006