用matlab解方程!!!急用!!!

发布网友 发布时间：2022-05-17 03:54

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共5个回答

热心网友 时间：2023-09-30 20:12

哇哈哈 看看我能拿到分么
首先需要把d化简出来，让d单独在一边

编写M文件
E0=20,L=8,I=4000;h=8
while h<=12
d=sqrt(sqrt((-8000*h/(4000*h/(256+h^2)^(3/2)-E0))^3)-256-h^2)
h=h+0.1
end
运行得结果
E0 =

20

L =

8

h =

8

d =

543.7584

h =

8.1000

d =

549.6379

h =

8.2000

d =

555.4887

h =

8.3000

d =

561.3102

h =

8.4000

d =

567.1020

h =

8.5000

d =

572.8634

h =

8.6000

d =

578.5942

h =

8.7000

d =

584.2937

h =

8.8000

d =

589.9617

h =

8.9000

d =

595.5975

h =

9.0000

d =

601.2010

h =

9.1000

d =

606.7718

h =

9.2000

d =

612.3094

h =

9.3000

d =

617.8136

h =

9.4000

d =

623.2841

h =

9.5000

d =

628.7206

h =

9.6000

d =

634.1230

h =

9.7000

d =

639.4909

h =

9.8000

d =

644.8242

h =

9.9000

d =

650.1227

h =

10.0000

d =

655.3862

h =

10.1000

d =

660.6147

h =

10.2000

d =

665.8081

h =

10.3000

d =

670.9662

h =

10.4000

d =

676.0889

h =

10.5000

d =

681.1764

h =

10.6000

d =

686.2284

h =

10.7000

d =

691.2451

h =

10.8000

d =

696.2264

h =

10.9000

d =

701.1725

h =

11.0000

d =

706.0832

h =

11.1000

d =

710.9588

h =

11.2000

d =

715.7993

h =

11.3000

d =

720.6048

h =

11.4000

d =

725.3755

h =

11.5000

d =

730.1114

h =

11.6000

d =

734.8128

h =

11.7000

d =

739.4798

h =

11.8000

d =

744.1126

h =

11.9000

d =

748.7114

h =

12.0000

d =

753.2764

h =

12.1000
现在你可以拟合了
另外你的问题1.matlab可以解带参数的方程 用solve即可
2.它程序中的syms 表示定义后面的函数 不然matlab无法识别 在m文件中编写可以免去定义
3.ans表示中间结果 比如你打a=2+3 结果为a=5 但是 你光打2+3 则结果为ans=5
4d的解与h的值 一一对应 自己看好了HOHO

热心网友 时间：2023-09-30 20:12

不好意思说一句：
你的d以平方形式存在，你该告诉大家要正值还是负值。
-------------------------------------
我的解法，解都是负数，也就是没实数解。方程错了自己改吧，全过程都给你了。
syms h d;
E0=20;
L=8;
I=4000;
I*h/(4*L^2+h^2)^(3/2)+2*I*h/(d^2+4*L^2+h^2)^(3/2)
ans =
4000*h/(256+h^2)^(3/2)+8000*h/(d^2+256+h^2)^(3/2)
>> solve('20=4000*h/(256+h^2)^(3/2)+8000*h/(d^2+256+h^2)^(3/2)','d')
Warning: Warning, solutions may have been lost
ans =
1/(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(-(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(1024*h^6+4294967296+77348864*h^2+433216*h^4-4*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)-102400*h*(256+h^2)^(3/2)+h^8-400*h^3*(256+h^2)^(3/2)))^(1/2)
-1/(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(-(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(1024*h^6+4294967296+77348864*h^2+433216*h^4-4*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)-102400*h*(256+h^2)^(3/2)+h^8-400*h^3*(256+h^2)^(3/2)))^(1/2)
1/(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(-(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(-2*i*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)*3^(1/2)+4294967296+77348864*h^2+433216*h^4+1024*h^6-102400*h*(256+h^2)^(3/2)+h^8-400*h^3*(256+h^2)^(3/2)+2*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)))^(1/2)
-1/(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(-(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(-2*i*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)*3^(1/2)+4294967296+77348864*h^2+433216*h^4+1024*h^6-102400*h*(256+h^2)^(3/2)+h^8-400*h^3*(256+h^2)^(3/2)+2*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)))^(1/2)
1/(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(-(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(2*i*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)*3^(1/2)+4294967296+77348864*h^2+433216*h^4+1024*h^6-102400*h*(256+h^2)^(3/2)+h^8-400*h^3*(256+h^2)^(3/2)+2*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)))^(1/2)
-1/(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(-(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(2*i*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)*3^(1/2)+4294967296+77348864*h^2+433216*h^4+1024*h^6-102400*h*(256+h^2)^(3/2)+h^8-400*h^3*(256+h^2)^(3/2)+2*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)))^(1/2)
>> for h=8:12
d=eval(ans)
end
d =
5.3213 +21.9867i
-5.3213 -21.9867i
5.3213 -21.9867i
-5.3213 +21.9867i
0.0000 - 7.0571i
-0.0000 + 7.0571i
d =
5.6290 +22.7242i
-5.6290 -22.7242i
5.6290 -22.7242i
-5.6290 +22.7242i
0.0000 - 6.4493i
-0.0000 + 6.4493i
d =
5.8881 +23.4551i
-5.8881 -23.4551i
5.8881 -23.4551i
-5.8881 +23.4551i
0.0000 - 6.0874i
-0.0000 + 6.0874i
d =
6.1027 +24.1791i
-6.1027 -24.1791i
6.1027 -24.1791i
-6.1027 +24.1791i
0.0000 - 6.0191i
-0.0000 + 6.0191i
d =
6.2774 +24.8972i
-6.2774 -24.8972i
6.2774 -24.8972i
-6.2774 +24.8972i
0.0000 - 6.2502i
-0.0000 + 6.2502i
>>

参考资料：http://www.matlabfan.com/?fromuid=1217

热心网友 时间：2023-09-30 20:13

不可能有解，你看光右边第一项已经大于E0了，右边第一项分子分母同时除以h^1.5，用简单的不等式知识就可以证明，这一项>E0,所以不可能有解，一定是方程的问题，或者参数错误

热心网友 时间：2023-09-30 20:13

syms h d
d=solve('4000*h/((4*64+h^2)^(3/2))+2*4000*h/(d^2+4*64+h^2)^(3/2)-1','d')
得到了六个结果

1/(16196608*h^2-8000*h*(256+h^2)^(3/2)+16777216+768*h^4+h^6)*(-(16196608*h^2-8000*h*(256+h^2)^(3/2)+16777216+768*h^4+h^6)*(16393216*h^4+4163108864*h^2-2048000*h*(256+h^2)^(3/2)+4294967296-400*(-h*(256+h^2)^(3/2)*(4000*h-(256+h^2)^(3/2))^2)^(2/3)+1024*h^6-8000*h^3*(256+h^2)^(3/2)+h^8))^(1/2)
-1/(16196608*h^2-8000*h*(256+h^2)^(3/2)+16777216+768*h^4+h^6)*(-(16196608*h^2-8000*h*(256+h^2)^(3/2)+16777216+768*h^4+h^6)*(16393216*h^4+4163108864*h^2-2048000*h*(256+h^2)^(3/2)+4294967296-400*(-h*(256+h^2)^(3/2)*(4000*h-(256+h^2)^(3/2))^2)^(2/3)+1024*h^6-8000*h^3*(256+h^2)^(3/2)+h^8))^(1/2)
1/(16196608*h^2-8000*h*(256+h^2)^(3/2)+16777216+768*h^4+h^6)*((16196608*h^2-8000*h*(256+h^2)^(3/2)+16777216+768*h^4+h^6)*(200*i*(-h*(256+h^2)^(3/2)*(4000*h-(256+h^2)^(3/2))^2)^(2/3)*3^(1/2)-4163108864*h^2+2048000*h*(256+h^2)^(3/2)-4294967296-16393216*h^4-1024*h^6+8000*h^3*(256+h^2)^(3/2)-h^8-200*(-h*(256+h^2)^(3/2)*(4000*h-(256+h^2)^(3/2))^2)^(2/3)))^(1/2)
-1/(16196608*h^2-8000*h*(256+h^2)^(3/2)+16777216+768*h^4+h^6)*((16196608*h^2-8000*h*(256+h^2)^(3/2)+16777216+768*h^4+h^6)*(200*i*(-h*(256+h^2)^(3/2)*(4000*h-(256+h^2)^(3/2))^2)^(2/3)*3^(1/2)-4163108864*h^2+2048000*h*(256+h^2)^(3/2)-4294967296-16393216*h^4-1024*h^6+8000*h^3*(256+h^2)^(3/2)-h^8-200*(-h*(256+h^2)^(3/2)*(4000*h-(256+h^2)^(3/2))^2)^(2/3)))^(1/2)
1/(16196608*h^2-8000*h*(256+h^2)^(3/2)+16777216+768*h^4+h^6)*(-(16196608*h^2-8000*h*(256+h^2)^(3/2)+16777216+768*h^4+h^6)*(200*i*(-h*(256+h^2)^(3/2)*(4000*h-(256+h^2)^(3/2))^2)^(2/3)*3^(1/2)+4163108864*h^2-2048000*h*(256+h^2)^(3/2)+4294967296+16393216*h^4+1024*h^6-8000*h^3*(256+h^2)^(3/2)+h^8+200*(-h*(256+h^2)^(3/2)*(4000*h-(256+h^2)^(3/2))^2)^(2/3)))^(1/2)
-1/(16196608*h^2-8000*h*(256+h^2)^(3/2)+16777216+768*h^4+h^6)*(-(16196608*h^2-8000*h*(256+h^2)^(3/2)+16777216+768*h^4+h^6)*(200*i*(-h*(256+h^2)^(3/2)*(4000*h-(256+h^2)^(3/2))^2)^(2/3)*3^(1/2)+4163108864*h^2-2048000*h*(256+h^2)^(3/2)+4294967296+16393216*h^4+1024*h^6-8000*h^3*(256+h^2)^(3/2)+h^8+200*(-h*(256+h^2)^(3/2)*(4000*h-(256+h^2)^(3/2))^2)^(2/3)))^(1/2)

好像看不清，自己运行一下吧，取符合条件的把函数式 复制一下，变量清空一下
h=8:0.01:12
d=结果复制到这边，注意加点就好了

热心网友 时间：2023-09-30 20:14

syms h d;
E0=20;
L=8;
I=4000;
I*h/(4*L^2+h^2)^(3/2)+2*I*h/(d^2+4*L^2+h^2)^(3/2)
ans =
4000*h/(256+h^2)^(3/2)+8000*h/(d^2+256+h^2)^(3/2)
>> solve('20=4000*h/(256+h^2)^(3/2)+8000*h/(d^2+256+h^2)^(3/2)','d')
Warning: Warning, solutions may have been lost
ans =
1/(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(-(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(1024*h^6+4294967296+77348864*h^2+433216*h^4-4*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)-102400*h*(256+h^2)^(3/2)+h^8-400*h^3*(256+h^2)^(3/2)))^(1/2)
-1/(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(-(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(1024*h^6+4294967296+77348864*h^2+433216*h^4-4*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)-102400*h*(256+h^2)^(3/2)+h^8-400*h^3*(256+h^2)^(3/2)))^(1/2)
1/(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(-(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(-2*i*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)*3^(1/2)+4294967296+77348864*h^2+433216*h^4+1024*h^6-102400*h*(256+h^2)^(3/2)+h^8-400*h^3*(256+h^2)^(3/2)+2*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)))^(1/2)
-1/(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(-(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(-2*i*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)*3^(1/2)+4294967296+77348864*h^2+433216*h^4+1024*h^6-102400*h*(256+h^2)^(3/2)+h^8-400*h^3*(256+h^2)^(3/2)+2*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)))^(1/2)
1/(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(-(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(2*i*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)*3^(1/2)+4294967296+77348864*h^2+433216*h^4+1024*h^6-102400*h*(256+h^2)^(3/2)+h^8-400*h^3*(256+h^2)^(3/2)+2*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)))^(1/2)
-1/(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(-(16777216+236608*h^2+768*h^4+h^6-400*h*(256+h^2)^(3/2))*(2*i*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)*3^(1/2)+4294967296+77348864*h^2+433216*h^4+1024*h^6-102400*h*(256+h^2)^(3/2)+h^8-400*h^3*(256+h^2)^(3/2)+2*(-50*h*(256+h^2)^(3/2)*(-(256+h^2)^(3/2)+200*h)^2)^(2/3)))^(1/2)
>> for h=8:12
d=eval(ans)
end
d =
5.3213 +21.9867i
-5.3213 -21.9867i
5.3213 -21.9867i
-5.3213 +21.9867i
0.0000 - 7.0571i
-0.0000 + 7.0571i
d =
5.6290 +22.7242i
-5.6290 -22.7242i
5.6290 -22.7242i
-5.6290 +22.7242i
0.0000 - 6.4493i
-0.0000 + 6.4493i
d =
5.8881 +23.4551i
-5.8881 -23.4551i
5.8881 -23.4551i
-5.8881 +23.4551i
0.0000 - 6.0874i
-0.0000 + 6.0874i
d =
6.1027 +24.1791i
-6.1027 -24.1791i
6.1027 -24.1791i
-6.1027 +24.1791i
0.0000 - 6.0191i
-0.0000 + 6.0191i
d =
6.2774 +24.8972i
-6.2774 -24.8972i
6.2774 -24.8972i
-6.2774 +24.8972i
0.0000 - 6.2502i
-0.0000 + 6.2502i
>>

参考资料： http://www.matlabfan.com/?fromuid=1217