We consider an inverse problem for finding the anomaly of discontinuous ele
ctrical conductivity by one current-voltage observation. We develop a real-
time algorithm for determining the location of the anomaly. This new idea i
s based on the observation of the pattern of a simple weighted combination
of the input current and the output voltage. Combined with an estimation of
size, this algorithm gives a good initial guess for Newton-type schemes. W
e give a rigorous proof for the location search algorithm. Both the mathema
tical analysis and its numerical implementation indicate our location searc
h algorithm is very fast, stable, and efficient. (C) 2002 John Wiley & Sons
, Inc.