function [sig,bet,gam] = Schnackgamsig(s,fu,fv,gu,gv,alpha,d);
%
    [fu,fv,gu,gv];
    temp = (d*fu+gv);
    cent = alpha*temp/(2*d);
    detJ = fu*gv - fv*gu;
    trJ  = fu+gv;
    shift = alpha*alpha*(detJ - temp^2/(4*d));
    gam = d*(s-cent).^2 + shift;
    bet = (d+1)*s - alpha*trJ;
    sig = real(.5*(-bet + sqrt(bet.*bet - 4*gam)));