内容简介作者简介 - 科学与工程计算系

zz=inline('x.^y','x','y');
nsx01=dblquad(zz,0,1,1,2)
nsx12=dblquad(zz,1,2,0,1)
nsx01 =
0.4055
nsx12 =
1.2293
4.8.2.2 内积分限为函数的二重积分
[double_int.m]
function SS=double_int(fun,innlow,innhi,outlow,outhi)
%double_int
%
%fun
%innlow,innhi
%outlow,outhi
y1=outlow;y2=outhi;x1=innlow;x2=innhi;f_p=fun;
SS=quad(@G_yi,y1,y2,[],[],x1,x2,f_p);
[G_yi.m]
function f=G_yi(y,x1,x2,f_p)
%G_yi
%y
%x1,x2
%
%f_p
y=y(:);n=length(y);
if isnumeric(x1)==1;xx1=x1*ones(size(y));else xx1=feval(x1,y);end
if isnumeric(x2)==1;xx2=x2*ones(size(y));else xx2=feval(x2,y);end
for i=1:n
f(i)=quad(f_p,xx1(i),xx2(i),[],[],y(i));
end
f=f(:);
【例 4.8.2.2-1】计算 I = ⎡
∫ ∫ x + y dx ⎤dy
⎢⎣ y
⎥⎦
4 2
2 2
( ) 。
1
(1)
[x_low.m]
function f=x_low(y)
f=sqrt(y);
(2)
(3)
ff=inline('x.^2+y.^2','x','y');
SS=double_int(ff,@x_low,2,1,4)
Warning: Minimum step size reached; singularity possible.
> In D:\MATLAB6P5\toolbox\matlab\funfun\quad.m at line 88
In D:\MATLAB6p5\work\G_yi.m at line 11
In D:\MATLAB6P5\toolbox\matlab\funfun\@inline\feval.m at line 20
In D:\MATLAB6P5\toolbox\matlab\funfun\quad.m at line 62
15