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[编程技巧] 为什么这个方程求不出解来?

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发表于 2007-6-23 18:25 | 显示全部楼层 |阅读模式

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x
o=[1 1 1];
  R=[1 1 1]
  fc1='f1-o(1)*R(1)-(0.02680082018562*o4^2-0.04986278743970*o4^4+0.13926356734790*o4^6+1.61192928400296*o4^8)*10^4=0';
   fc2='f2-o(2)*R(2)-(0.01506052036199*o5^2-0.03383474361318*o5^4+0.10813482170574*o5^6+1.37193165556870*o5^8)*10^4+o(1)*R(1)-f1=0';
   fc3='f3-o(3)*R(3)-(0.01506052036199*o6^2-0.03383474361318*o6^4+0.10813482170574*o6^6+1.37193165556870*o6^8)*10^4+o(2)*R(2)-f2=0';
   fc4='f3-o(3)*R(3)+(0.02680082018562*o7^2-0.04986278743970*o7^4+0.13926356734790*o7^6+1.61192928400296*o7^8)*10^4=0';
   fc5='o(1)+o5-o4=0';
   fc6='o(2)+o6-o5=0';
   fc7='o(3)+o7-o6=0';
   fc1=subs(fc1,'o',o(1));fc1=subs(fc1,'o',o(2));fc1=subs(fc1,'o',o(3));
   fc1=subs(fc1,'R',R(1));fc1=subs(fc1,'R',R(2));fc1=subs(fc1,'R',R(3));
   fc2=subs(fc2,'o',o(1));fc2=subs(fc2,'o',o(2));fc2=subs(fc2,'o',o(3));
   fc2=subs(fc2,'R',R(1));fc2=subs(fc2,'R',R(2));fc2=subs(fc2,'R',R(3));
   fc3=subs(fc3,'o',o(1));fc3=subs(fc3,'o',o(2));fc3=subs(fc3,'o',o(3));
   fc3=subs(fc3,'R',R(1));fc3=subs(fc3,'R',R(2));fc3=subs(fc3,'R',R(3));
   fc4=subs(fc4,'o',o(1));fc3=subs(fc4,'o',o(2));fc4=subs(fc4,'o',o(3));
   fc4=subs(fc4,'R',R(1));fc3=subs(fc4,'R',R(2));fc4=subs(fc4,'R',R(3));
   fc5=subs(fc5,'o',o(1));fc3=subs(fc5,'o',o(2));fc5=subs(fc5,'o',o(3));
   fc5=subs(fc5,'R',R(1));fc3=subs(fc5,'R',R(2));fc5=subs(fc5,'R',R(3));
   fc6=subs(fc6,'o',o(1));fc3=subs(fc6,'o',o(2));fc6=subs(fc6,'o',o(3));
   fc6=subs(fc6,'R',R(1));fc3=subs(fc6,'R',R(2));fc6=subs(fc6,'R',R(3));
   fc7=subs(fc7,'o',o(1));fc3=subs(fc7,'o',o(2));fc7=subs(fc7,'o',o(3));
   fc7=subs(fc7,'R',R(1));fc3=subs(fc7,'R',R(2));fc7=subs(fc7,'R',R(3));
   [f1 f2 f3 o4 o5 o6 o7]=solve(fc1,fc2,fc3,fc4,fc5,fc6,fc7)
结果 是
f1 =

17282.308840967800000000000000000+928538.60101364960000000000000000*o5^3+16119.292840029600000000000000000*o5^8+469505.97557848800000000000000000*o5^2+1148741.4060298600000000000000000*o5^4+452732.83519430780000000000000000*o5^6+135851.66166723520000000000000000*o5+128954.34272023680000000000000000*o5^7+911036.21308253160000000000000000*o5^5


f2 =

469656.58078210790000000000000000*o5^2+1148403.0585937282000000000000000*o5^4+453814.18341136520000000000000000*o5^6+29838.609395716600000000000000000*o5^8+17282.308840967800000000000000000+928538.60101364960000000000000000*o5^3+135851.66166723520000000000000000*o5+128954.34272023680000000000000000*o5^7+911036.21308253160000000000000000*o5^5


f3 =

29104605.454094507200000000000000*o5^3-16119.292840029600000000000000000*o5^8-29208306.270184331400000000000000*o5^2-18136667.493367495000000000000000*o5^4-1806753.4337567942000000000000000*o5^6+16758657.858324999200000000000000*o5+257908.68544047360000000000000000*o5^7+7238154.8204150088000000000000000*o5^5-4208760.6369673064000000000000000


o4 =

1.+o5


o5 =

o5


o6 =

-1.+o5


o7 =

-2.+o5

请问下是为什么啊?是7个方程7个未知数,为什么结果里o5是个符号呢?

[ 本帖最后由 icefree520 于 2007-6-23 18:26 编辑 ]
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发表于 2007-6-23 19:14 | 显示全部楼层
可以侃侃这两个式子
fc2='f2-o(2)*R(2)-(0.01506052036199*o5^2-0.03383474361318*o5^4+0.10813482170574*o5^6+1.37193165556870*o5^8)*10^4+o(1)*R(1)-f1=0';
   fc3='f3-o(3)*R(3)-(0.01506052036199*o6^2-0.03383474361318*o6^4+0.10813482170574*o6^6+1.37193165556870*o6^8)*10^4+o(2)*R(2)-f2=0';
我觉得问题就出在这两个上

[ 本帖最后由 eight 于 2007-6-25 10:42 编辑 ]
发表于 2007-6-23 21:08 | 显示全部楼层
估计你这几个函数是相关的

同意楼上的看法
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