function solve_n_eqs
clear all;clc
d=45;
D=150;
n=5000;   
x=linspace(-0.0005,0.001,n);
y=0.1248*x.^4.*( 1./(pi*d-0.2*x)-1./(pi*D-0.2*x)   )+0.2496*x.^3.*log(abs( (pi*D-0.2*x)./(pi*d-0.2*x)  ))+1.248*pi*x.^2*(D-d)-0.2*x.^3*(D^3-d^3)    ;
figure(1)
plot(x,y,'b',[min(x) max(x)],[0 0],'r'),axis([min(x) max(x) min(y) max(y)]);

format long

[x fval]=fsolve(@(x) 0.1248*x.^4.*( 1./(pi*d-0.2*x)-1./(pi*D-0.2*x)   )+0.2496*x.^3.*log(abs( (pi*D-0.2*x)./(pi*d-0.2*x)  ))+1.248*pi*x.^2*(D-d)-0.2*x.^3*(D^3-d^3),[1e-5 1e-3])

5楼: Originally posted by 月只蓝 at 2016-03-24 13:09:52
function solve_n_eqs
clear all;clc
d=45;
D=150;
n=5000;   
x=linspace(-0.0005,0.001,n);
y=0.1248*x.^4.*( 1./(pi*d-0.2*x)-1./(pi*D-0.2*x)   )+0.2496*x.^3.*log(abs( (pi*D-0.2*x)./(pi*d-0.2*x)   ...

6楼: Originally posted by 1275322766 at 2016-03-25 09:35:35
结果不是这样的，应该在该在120~150之间吧，这和我想要的结果相差甚远！不过还是非常感谢你的！...