如何用MATLAB求解矩阵方程、定积分 定积分上下限能否用字母代替
\u600e\u6837\u7528MATLAB\u6c42\u89e3\u5b9a\u79ef\u5206\u65b9\u7a0b\u4e2d\u7684\u53c2\u53d8\u91cf\uff1f.m\u6587\u4ef6
function A=qfun(c)
L = 1;
F = 0.1;
s=0;
fun=@(u,x)(1+((F^2)/(x^4))*(1-cos(pi/2*L*x*u)/cos(pi/2*L*x)).^2).^(1/2);
A=quad(@(u)fun(u,c),0,1)-1/L;
==================================
[x,feval]=fsolve(@qfun,2,optimset('Display','off','TolX',1e-8,'TolFun',1e-8))
x =
3.5750
feval =
6.1805e-005
\u597d\u5427\uff0c\u518d\u4fee\u6539\u6210
|K-w^2*M|=0
\u5b9e\u9645\u4e0a\u5c31\u662f\u4e2a\u4e09\u6b21\u591a\u9879\u5f0f\u7684\u6c42\u89e3
\u7a0b\u5e8f\uff1a
syms v
M=[2 1 0 0;1 4 1 0;0 1 4 1;0 0 1 2]
K=[1 -1 0 0;-1 2 -1 0;0 -1 2 -1;0 0 -1 1]
f=det(K-v*M)
solve(f)
\u6c42\u51fa\u4e86v\uff0cw\u5c31\u662fv\u7684\u5f00\u65b9\uff0c\u4f60\u5e94\u8be5\u4f1a\u6c42\u5427
例如
1）AX=b %X=inv(A)*b
>> A=[1 2 3; 5 8 8;6 2 7]
A =
1 2 3
5 8 8
6 2 7
>> b=[3; 7; 2]
b =
3
7
2
>> X=inv(A)*b
X =
-1.0000
0.5000
1.0000
或
>> X=A\b
X =
-1.0000
0.5000
1.0000
2)定积分
>> syms x a b
>>F＝ int(sin(x),a,b)
F =-cos(b)+cos(a)
例如
1）AX=b %X=inv(A)*b
>> A=[1 2 3; 5 8 8;6 2 7]
A =
1 2 3
5 8 8
6 2 7
>> b=[3; 7; 2]
b =
3
7
2
>> X=inv(A)*b
X =
-1.0000
0.5000
1.0000
或
>> X=A\b
X =
-1.0000
0.5000
1.0000
2)定积分
>> syms x a b
>>F＝ int(sin(x),a,b)
F =-cos(b)+cos(a)
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