matlab 等式化简,用Matlab化简一个复杂含参积分式的函数表达式 - 程序语言 - 小木虫 - 学术科研互动社区...

梦里梦外; 2023-01-13 10:15 45阅读 0赞

![cfdc6361174d9cfc8169daed13483a0c.gif][]

月只蓝

“数值解分别计算一个一个案例”，对于不同的案例，积分式什么参数会改变？

![noavatar.png][]

daijiantao

引用回帖:

月只蓝 at 2016-04-07 13:51:21

“数值解分别计算一个一个案例”，对于不同的案例，积分式什么参数会改变？

M N exp n wf0 tH会变。所以想找一个含参的近似方程，怎样用MATLAB实现呢~

![d68c772fe4d681640cb4c64e8f61f157.png][]

wyyacgh

用mathmetica试试吧

![cfdc6361174d9cfc8169daed13483a0c.gif][]

月只蓝

引用回帖:

daijiantao at 2016-04-07 23:45:21

M N exp n wf0 tH会变。所以想找一个含参的近似方程，怎样用MATLAB实现呢~...

M N exp n wf0 tH会变，写个循环语句就解决了。

原积分式即便近似为一个代数式，M N exp n wf0 tH会变的情况下，一样麻烦。

![noavatar.png][]

daijiantao

引用回帖:

月只蓝 at 2016-04-08 09:30:09

M N exp n wf0 tH会变，写个循环语句就解决了。

原积分式即便近似为一个代数式，M N exp n wf0 tH会变的情况下，一样麻烦。...

如果我只有积分上限变化(tH)，其余都不变，能基于上面的程序帮忙给一个程序吗，最好可以出图？

![6569392bbddb676f76f819e41db3bdb3.gif][]

ybkooo

syms p1 p2 p3 p4 p5 tH t

F = (((p1./(1+t)-p2.\*log10(1+t)./(1+t)).^p3./p4)-(p1./(1+t)-p2.\*log10(1+t)./(1+t))./p5);

ff=int(F,t,0,tH);

latex(ff)

结果(不咋的)：

ans =

\\int \_\{0\}^\{ \{\\it tH\}\}\\! \\left( \{\\frac \{ \{\\it p1\}\}\{1+t\}\}-\{\\frac \{ \{\\it p2\}\\,\\ln  \\left( 1+t \\right) \}\{\\ln  \\left( 10 \\right)  \\left( 1+t \\right) \}\} \\right) ^\{ \{\\it p3\}\}\{ \{\\it p4\}\}^\{-1\}- \\left( \{\\frac \{ \{\\it p1\}\}\{1+t\}\}-\{\\frac \{ \{\\it p2\}\\,\\ln  \\left( 1+t \\right) \}\{\\ln  \\left( 10 \\right)  \\left( 1+t \\right) \}\} \\right) \{ \{\\it p5\}\}^\{-1\}\{dt\}

![cfdc6361174d9cfc8169daed13483a0c.gif][]

月只蓝

引用回帖:

daijiantao at 2016-04-10 23:15:42

如果我只有积分上限变化(tH)，其余都不变，能基于上面的程序帮忙给一个程序吗，最好可以出图？...

以下代码是积分上限tH从100开始以间隔1变化到600的例子，可自行根据实际修改。

需注意以下代码为m文件格式，请新建一个m文件，把以下代码完整复制进去，再运行。CODE:

function qiu\_jifen

clear all;clc

format long

tH\_0=100;    %积分上限tH的最小值

tH\_n=500;    %积分上限tH的最大值

num=tH\_n-tH\_0+1;     %积分上限tH总的变化数目

tH\_data=linspace(tH\_0,tH\_n,num);

for i=1:length(tH\_data)

tH=tH\_data(i);

dc(i)=quadgk(@obj,0,tH);

end

\[tH\_data' dc'\]

figure(1)

plot(tH\_data,dc,'b-')

function f=obj(t)

M=0.230873094;

N=0.025914445;

n=0.86;

exp=114.8;

wf0=46;

p1=M;

p2=N;

p3=n;

p4=exp;

p5=wf0;

f=(((p1./(1+t)-p2.\*log10(1+t)./(1+t)).^p3./p4)-(p1./(1+t)-p2.\*log10(1+t)./(1+t))./p5);

计算结果：

积分上限tH          数值积分结果

ans =

1.0e+002 \*

1.000000000000000  -0.000062764008049

1.010000000000000  -0.000062774137557

1.020000000000000  -0.000062783623116

1.030000000000000  -0.000062792482273

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4.630000000000000  -0.000057668919801

4.640000000000000  -0.000057652138576

4.650000000000000  -0.000057635366187

4.660000000000000  -0.000057618602654

4.670000000000000  -0.000057601847995

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![w134h1122189\_1460340040\_588.png][w134h1122189_1460340040_588.png]

附图1.png

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