function YY=fc4(X) %函數(shù)表達(dá)式文件：三元方程（已化簡）%
% 定義一個(gè)函數(shù)，x為船上聲吶的位置數(shù)據(jù) %
% R為應(yīng)答器到船上聲吶的距離 %
% X0為布放時(shí)應(yīng)答器的位置 %
% A 為矢量水聽器測得的角度 %
global xx
global A
global R
global aa

y1=(X(1)-xx(1,1))^2+(X(2)-xx(1,2))^2+(X(3)-xx(1,3))^2-R(1,1)^2; %方程1
y2=(X(1)-xx(2,1))^2+(X(2)-xx(2,2))^2+(X(3)-xx(2,3))^2-R(2,1)^2; %方程2
%xxx=(sin(A)).^2.*(R(1).^2-(X(3)-xx(1,3)).^2)-(X(1)-xx(1,1)).^2;

l11=sqrt((xx(1,1)-xx(2,1))^2+(xx(1,2)-xx(2,2))^2);
%l12=R(1,1)^2-(X(3)-xx(1,3))^2;
%l13=R(2,1)^2-(X(3)-xx(2,3))^2;
%y3=l12+l13-2*sqrt(l12*l13)*cos(aa)-l11^2;
r1=(X(1)-xx(1,1))^2+(X(2)-xx(1,2))^2;
r2=(X(1)-xx(2,1))^2+(X(2)-xx(2,2))^2;
y3=r1+r2-2*sqrt(r1)*sqrt(r2)*cos(aa)-l11^2; %方程3
YY=[y1 y2 y3];