二重积分求值

uaidenp · 发表于 2020-7-1 15:09

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x

计算二重积分的时候，结果就是一个式子，不是积分值，这是为什么呢？求教

代码如下：

clear all
close all
clc
syms x y
omega=1;
mu=0.001;
alpha=0.13;
beta=0.0031;
u=0.001;v=-0.02;
tau=2.2;tau1=1.5;D=0.11;
tau01=1.42;tau02=1.5;tau03=1.56;tau04=1.9;
omega2=1-u*cos(omega*tau)-v*omega*sin(omega*tau01);
eta=1+(1/mu)*(-(u/omega)*sin(omega*tau)+v*cos(omega*tau01));
K=D/(omega2.*(1+omega2.*(tau1.^2)));
f1=(1./(omega2.*K)).*exp(-(mu./(1536.*K)).*(15.*beta.*(x.^2+y.^2./omega2).^4-32.*alpha.*(x.^2+y.^2./omega2).^3+96.*(x.^2+y.^2./omega2).^2-768.*eta.*(x.^2+y.^2./omega2)));
F1=int(int(f1,x,0,10),y,-10,10)

结果：
F1=
int(int((1029484437153*exp((76368780973521777*(x^2 + (2251799813685248*y^2)/2297649917499219)^3)/922337203685477580800 - (17623564840043487*(x^2 + (2251799813685248*y^2)/2297649917499219)^2)/9223372036854775808 - (546330510041348097*(x^2 + (2251799813685248*y^2)/2297649917499219)^4)/590295810358705651712000 - (3488543873076974433998624506509*x^2)/81129638414606681695789005144064 - (1162847957692324811332874835503*y^2)/27593854166072889506733609713664))/34359738368, x, 0, 10), y, -10, 10)