| 查看: 1179 | 回复: 5 | ||
chaofan1231银虫 (小有名气)
|
[求助]
matlab解代数方程的问题
|
|
|
哪位大侠帮忙看下这是怎么回事啊？谢谢啊 y=2; >> subs(solve('y=exp((1/0.0000005461-1/0.000000700)*0.014388/x+ln((x-993.74731)/2869.03078)-5*ln(700/546.1))','x')) Warning: Explicit solution could not be found. 我把y=2直接代进去的话solve('2=exp((1/0.0000005461-1/0.000000700)*0.014388/x+ln((x-993.74731)/2869.03078)-5*ln(700/546.1))','x') ans =matrix([[14197.808632879686391435779145547]])，但是我在origin中将这个方程画成曲线的话，y=2时x的两个值分别在1100和1900附近，这是怎么回事啊？ |
回复此楼» 猜你喜欢
一志愿085802 323分求调剂
已经有11人回复
-
山东双非院校考核超级无底线，领导幸灾乐祸，教师遭殃恐
已经有7人回复
-
279学硕食品专业求调剂院校
已经有17人回复
-
一志愿安大生物学07初试322、本科二本、调剂求助
已经有9人回复
-
一志愿浙大生物325分求调剂
已经有7人回复
-
化学070300 求调剂
已经有9人回复
-
085600材料与化工349分求调剂
已经有5人回复
-
297工科，求调剂?
已经有6人回复
-
考研求调剂
已经有3人回复
-
材料相关专业344求调剂双非工科学校或课题组
已经有8人回复
» 本主题相关价值贴推荐，对您同样有帮助:
- 求matlab 解方程的问题
已经有5人回复
- 【活动】学习软件，推荐书活动（有BB奖励哟）
已经有51人回复
- 【求助】高维PDE的求解
已经有11人回复
【答案】应助回帖
★ ★ ★ ★ ★
chaofan1231: 金币+5, ★★★★★最佳答案 2012-05-15 14:53:43
chaofan1231: 回帖置顶 2012-05-15 14:54:44
chaofan1231: 金币+5, ★★★★★最佳答案 2012-05-15 14:53:43
chaofan1231: 回帖置顶 2012-05-15 14:54:44
|
>> evalin(symengine, 'numeric::solve(2=exp((1/0.0000005461-1/0.000000700)*0.014388/x+ln((x-993.74731)/2869.03078)-5*ln(700/546.1)), x = 1000..2000)') ans = 1092.7957902606343947864233870012 >> evalin(symengine, 'numeric::solve(2=exp((1/0.0000005461-1/0.000000700)*0.014388/x+ln((x-993.74731)/2869.03078)-5*ln(700/546.1)), x = 1500..2000)') ans = 1826.2296709384982930177909403237 Solve the following equation: syms x; solve('sin(x) = x^2 - 1') The symbolic solver cannot find an exact symbolic solution for this equation, and therefore, it calls the numeric solver. Because the equation is not polynomial, an attempt to find all possible solutions can take a long time. The numeric solver does not try to find all numeric solutions for this equation. Instead, it returns only the first solution that it finds: ans = -0.63673265080528201088799090383828 Plotting the left and the right sides of the equation in one graph shows that the equation also has a positive solution: ezplot(sin(x), -2, 2); hold on; ezplot(x^2 - 1, -2, 2) hold off You can find this solution by calling the MuPAD numeric solver directly and specifying the interval where this solution can be found. To call MuPAD commands from the MATLAB Command Window, use the evalin or feval function: evalin(symengine, 'numeric::solve(sin(x) = x^2 - 1, x = 0..2)') ans = 1.4096240040025962492355939705895 |
» 本帖已获得的红花（最新10朵）
5楼2012-05-15 09:18:57
2楼2012-05-14 10:01:04
3楼2012-05-14 10:01:30
chaofan1231
银虫 (小有名气)
- 应助: 29 (小学生)
- 金币: 1599
- 帖子: 240
- 在线: 89.3小时
- 虫号: 1243032
- 注册: 2011-03-23
- 性别: GG
- 专业: 资源化工
4楼2012-05-15 08:05:50
chaofan1231
银虫 (小有名气)
送鲜花一朵
 |
6楼2012-05-15 14:54:04
20