内容简介作者简介 - 科学与工程计算系

0.0017
exitflag =
1
4.6.3 多元函数的零点
⎧ f1(
x,
y)
= sin( x − y)
= 0
【例 4.6.3-1】求解二元函数方程组 ⎨
的零点。
⎩ f 2 ( x,
y)
= cos( x + y)
= 0
(1)
x=-2:0.5:2;y=x;[X,Y]=meshgrid(x,y);
F1=sin(X-Y);F2=cos(X+Y);
v=[-0.2, 0, 0.2];
contour(X,Y,F1,v)
hold on,contour(X,Y,F2,v),hold off
1.5
0.5
0
-0.5
-1
-1.5
(2)
[x0,y0]=ginput(2);
disp([x0,y0])
-0.7926 -0.7843
0.7926 0.7843
2
1
-2
-2 -1.5 -1 -0.5 0 0.5 1 1.5 2
图 4.6-3
(3)
fun='[sin(x(1)-x(2)),cos(x(1)+x(2))]'; %
[xy,f,exit]=fsolve(fun,[x0(2),y0(2)]) %
Optimization terminated successfully:
First-order optimality less than OPTIONS.TolFun, and no negative/zero
curvature detected
xy =
0.7854 0.7854
f =
1.0e-006 *
-0.0984 0.2011
exit =
1
〖说明〗
[fun.m]
function ff=fun(x)
ff(1)=sin(x(1)-x(2));
ff(2)=cos(x(1)+x(2));
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