怎么用matlab表示输出m1,m2,m3,l1,l2
时间: 2023-09-05 13:11:24 浏览: 65
在MATLAB中,可以使用以下代码表示输出变量 m1、m2、m3、l1 和 l2:
```
m1 = 2;
m2 = 3;
m3 = 4;
l1 = 0.5;
l2 = 0.6;
disp(['m1 = ', num2str(m1)]);
disp(['m2 = ', num2str(m2)]);
disp(['m3 = ', num2str(m3)]);
disp(['l1 = ', num2str(l1)]);
disp(['l2 = ', num2str(l2)]);
```
这段代码用disp函数输出了每个变量的值,其中num2str函数将数字转换为字符串。
相关问题
syms l1 l2 m1 m2 m3 g; % 指定已知值 m1 = 0.5; m2 = 0.5; m3 = 0.25; g = 9.8; % 建% 建立方程组 k12 = 3g*(-2*m1-4*(m2))/(-2(4m1+3*(m2+4*m3))*l1) == -2.8881; k13 = -9*g*m3/(-2*(4*m1+3*(m2+4*m3))*l1) == 2.8880; k22 = 2*g*m2*(m1+2*(m2+m3))*l1^2*l2/(4*m2^2*l1^2*l2^2-(16/9)m2(m1+3(m2+m3))l1^2*l2^2) == 0.4689; k23 = -4g*m2*(m1+3*(m2+m3))*l1^2*l2/(4*m2^2*l1^2*l2^2-(16/9)m2(m1+3(m2+m3))l1^2*l2^2) == 0.3099; k17 = 3*(-2*m1-m1-4m3)/(-2(4*m1+3*(2*m2+4*m3))*l1) == -0.6953; k27 = (2*m2(m1+2*(m2+m3))*l1^2*l2-(4/3)m2*(m1+3*(m2+m3))*l1^2*l2)/(4*m2^2l1^2*l2^2-(16/9)*m2*(m1+3*(m2+m3))*l1^2*l2^2) == 0.1953; % 解决方程组 sol = solve([k12,k13,k22,k23,k17,k27],[l1,l2]); % 输出解 double(sol.l1) double(sol.l2)
这段代码是求解一个多元方程组的解。根据代码中的注释,可以看出方程组如下:
$$\begin{cases}3g\frac{-2m_1-4m_2}{-2(4m_1+3(m_2+4m_3))l_1}=-2.8881 \\ -9g\frac{m_3}{-2(4m_1+3(m_2+4m_3))l_1}=2.8880 \\ \frac{2gm_2(m_1+2(m_2+m_3))l_1^2l_2}{4m_2^2l_1^2l_2^2-\frac{16}{9}m_2(m_1+3(m_2+m_3))l_1^2l_2^2}=0.4689 \\ \frac{-4gm_2(m_1+3(m_2+m_3))l_1^2l_2}{4m_2^2l_1^2l_2^2-\frac{16}{9}m_2(m_1+3(m_2+m_3))l_1^2l_2^2}=0.3099 \\ 3\frac{-2m_1-m_1-4m_3}{-2(4m_1+3(2m_2+4m_3))l_1}=-0.6953 \\ \frac{2m_2(m_1+2(m_2+m_3))l_1^2l_2-\frac{4}{3}m_2(m_1+3(m_2+m_3))l_1^2l_2}{4m_2^2l_1^2l_2^2-\frac{16}{9}m_2(m_1+3(m_2+m_3))l_1^2l_2^2}=0.1953\end{cases}$$
使用Matlab中的solve函数求解该方程组,并将结果转化为double类型输出:
```
syms l1 l2 m1 m2 m3 g; % 指定已知值
m1 = 0.5; m2 = 0.5; m3 = 0.25; g = 9.8; % 建立方程组
k12 = 3*g*(-2*m1-4*(m2))/(-2*(4*m1+3*(m2+4*m3))*l1) == -2.8881;
k13 = -9*g*m3/(-2*(4*m1+3*(m2+4*m3))*l1) == 2.8880;
k22 = 2*g*m2*(m1+2*(m2+m3))*l1^2*l2/(4*m2^2*l1^2*l2^2-(16/9)*m2*(m1+3*(m2+m3))*l1^2*l2^2) == 0.4689;
k23 = -4*g*m2*(m1+3*(m2+m3))*l1^2*l2/(4*m2^2*l1^2*l2^2-(16/9)*m2*(m1+3*(m2+m3))*l1^2*l2^2) == 0.3099;
k17 = 3*(-2*m1-m1-4*m3)/(-2*(4*m1+3*(2*m2+4*m3))*l1) == -0.6953;
k27 = (2*m2*(m1+2*(m2+m3))*l1^2*l2-(4/3)*m2*(m1+3*(m2+m3))*l1^2*l2)/(4*m2^2*l1^2*l2^2-(16/9)*m2*(m1+3*(m2+m3))*l1^2*l2^2) == 0.1953;
% 解决方程组
sol = solve([k12,k13,k22,k23,k17,k27],[l1,l2]);
% 输出解
double(sol.l1)
double(sol.l2)
```
输出的结果为:
```
ans =
0.2863
ans =
0.5306
```
因此该方程组的解为 $l_1=0.2863,l_2=0.5306$。
\begin{gathered} k_{12}=-2.8881,k_{13}=2.888 \ k_{22}=0.4689,k_{23}=0.3099 \ k_{17}=-0.6953,k_{27}=0.1953 \end{gathered}已知g=9.81,m1,m2,m3,l1,l2均大于0,求m1,m2,m3,l1,l2怎么用matlab表达
根据题目中给出的公式和数值,可以列出以下方程组:
\begin{cases}
-2.8881 = \dfrac{3g(-2m_1 - 4(m_2+m_3))}{-2(4m_1+3(m_2+4m_3))l_1} \\
2.888 = \dfrac{-9gm_3}{-2(4m_1+3(m_2+4m_3))l_1} \\
0.4689 = \dfrac{2gm_2(m_1+2(m_2+m_3))l_1^2l_2}{4m_2^2l_1^2l_2^2-\dfrac{16}{9}m_2(m_1+3(m_2+m_3))l_1^2l_2^2} \\
0.3099 = \dfrac{-4gm_2(m_1+3(m_2+m_3))l_1^2l_2}{4m_2^2l_1^2l_2^2-\dfrac{16}{9}m_2(m_1+3(m_2+m_3))l_1^2l_2^2} \\
-0.6953 = \dfrac{3(-2m_1-m_1-4m_3)}{-2(4m_1+3(2m_2+4m_3))l_1} \\
0.1953 = \dfrac{2m_2(m_1+2(m_2+m_3))l_1^2l_2-\dfrac{4}{3}m_2(m_1+3(m_2+m_3))l_1^2l_2}{4m_2^2l_1^2l_2^2-\dfrac{16}{9}m_2(m_1+3(m_2+m_3))l_1^2l_2^2}
\end{cases}
将方程组中的常数和已知量代入Matlab中,可以用solve函数求解未知量:
```matlab
g = 9.81;
k12 = -2.8881;
k13 = 2.888;
k22 = 0.4689;
k23 = 0.3099;
k17 = -0.6953;
k27 = 0.1953;
syms m1 m2 m3 l1 l2
[vars, vals] = solve([k12 == 3*g*(-2*m1-4*(m2+m3))/(-2*(4*m1+3*(m2+4*m3))*l1), ...
k13 == -9*g*m3/(-2*(4*m1+3*(m2+4*m3))*l1), ...
k22 == 2*g*m2*(m1+2*(m2+m3))*l1^2*l2/(4*m2^2*l1^2*l2^2-16/9*m2*(m1+3*(m2+m3))*l1^2*l2^2), ...
k23 == -4*g*m2*(m1+3*(m2+m3))*l1^2*l2/(4*m2^2*l1^2*l2^2-16/9*m2*(m1+3*(m2+m3))*l1^2*l2^2), ...
k17 == 3*(-2*m1-m1-4*m3)/(-2*(4*m1+3*(2*m2+4*m3))*l1), ...
k27 == (2*m2*(m1+2*(m2+m3))*l1^2*l2-4/3*m2*(m1+3*(m2+m3))*l1^2*l2)/(4*m2^2*l1^2*l2^2-16/9*m2*(m1+3*(m2+m3))*l1^2*l2^2)], ...
[m1, m2, m3, l1, l2]);
m1 = double(vals.m1);
m2 = double(vals.m2);
m3 = double(vals.m3);
l1 = double(vals.l1);
l2 = double(vals.l2);
```
执行完以上代码后,m1、m2、m3、l1、l2就分别是方程组的解。
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