BICG   BiConjugate Gradients Method.
 
    X = bicg(A,B) attempts to solve the linear system A*X=B via the
    BICG method.
 
    This routine is simply a wrapper to Matlab's own BICGS routine,
    and the argument list variations described in Matlab's BICG
    documentation are also allowed here.  The usage is identical to
    Matlab's default version, except that the first argument must be a
    Spot operator.