roya 发表于 2006-12-8 20:26

(求助)如何用matlab求解超越方程精确解

我在求解下列超越方程时遇到如下问题,请问各位高手,如下方程改如何求解?万分感谢!
>> solve('(2*n-1)*(n-1)*sqrt(n)*x/tan(sqrt(n)*x)+n*(2*n-3)*sqrt(n-1)*x/tan(sqrt(n-1)*x)=1','x')
??? Error using ==> solve
Error, (in allvalues/rootseq) cannot evaluate with symbolic coefficients

xjzuo 发表于 2006-12-9 10:03

回复

这个问题基本上不能解析求解,我用Mathematica也算了一下,证实了这点.
即使给定n值,x也有很多解,所以建议数值求解.
后者可以通过循环实现各个n值下的一系列解x,图形也可以很容易绘出.

hunter_009 发表于 2006-12-9 11:02

超越方程有没有解析解还是问号呢?,如果没有,那你为什么要求精确解呢。

zh5026 发表于 2007-6-4 14:58

遇到同样的问题
还请高手明示哈
n 循环的范围是什么?

dingd 发表于 2007-6-4 16:37

一组解:
n x
1.5 1.30137873884342E-08
1.6 .875350337485311
1.7 1.03868253265214
1.8 1.09982865773199
1.9 1.12072878952148
2 1.12254698836177
2.1 1.11451456798482
2.2 1.1012160174405
2.3 1.08511934220077
2.4 1.06762541354573
2.5 1.04955722941532
2.6 1.0314080272017
2.7 1.01347532527426
2.8 .995936990327688
2.9 .978896125242108
3 .962408403942755
3.1 .946499146248204
3.2 .93117420503426
3.3 .916427022317106
3.4 .902243260098473
3.5 .88860386683614
3.6 .875487118736107
3.7 .862869980286791
3.8 .850729007835507
3.9 .839040943813506
4 .827783100230926
4.1 .816933598074311
4.2 .806471508056846
4.3 .796376923969823
4.4 .786630990257224
4.5 .777215898846077
4.6 .768114865716578
4.7 .759312094532589
4.8 .750792732439494
4.9 .742542821579339
5 .734549248773676
5.1 .726799695045976
5.2 .71928258610352
5.3 .711987044507368
5.4 .704902843982281
5.5 .698020366123541
5.6 .691330559621399
5.7 .68482490202976
5.8 .678495364041798
5.9 .672334376192982
6 .666334797885252
6.1 .660489888610382
6.2 .654793281242645
6.3 .649238957268418
6.4 .643821223821588
6.5 .638534692397412
6.6 .633374259122795
6.7 .628335086467315
6.8 .623412586286165
6.9 .618602404093221
7 .613900404469496
7.1 .609302657519056
7.2 .604805426291081
7.3 .600405155093003
7.4 .596098458625494
7.5 .59188211187562
7.6 .587753040709565
7.7 .583708313111057
7.8 .579745131016043
7.9 .575860822698134
8 .572052835663109
8.1 .568318730014127
8.2 .564656172252431
8.3 .561062929481203
8.4 .557536863982837
8.5 .554075928142281
8.6 .55067815969134
8.7 .547341677250781
8.8 .544064676148973
8.9 .540845424497449
9 .537682259505314
9.1 .534573584015861
9.2 .531517863250012
9.3 .528513621742409
9.4 .525559440457066
9.5 .522653954070463
9.6 .519795848410902
9.7 .516983858043773
9.8 .514216763993132
9.9 .511493391590728
10 .50881260844424

M-Scofield 发表于 2009-10-18 11:11

感谢楼上解答,我正在找这方面问题解答
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