Problems in solve iteratively calculation
2 次查看(过去 30 天)
显示 更早的评论
Hi everyone, I'm newbie in Matlab. I'm trying to solve an equation iteratively, but the answer showed is different from my calculator.
syms dt2;
solve((-2.4638*cos(dt2))-dt2 + 2.6628 == 0.0785,dt2)
The answer that I expect is 0.700201189 (I found it in my calculator), but I have 0.14711303119198522137688950797546 in Matlab.
Along with the answer, it shows a messagem:
"Warning: Cannot solve symbolically. Returning a numeric approximation instead."
采纳的回答
Ameer Hamza
2020-5-29
If you look at the graph of this equation, you can see that it has two solutions in the interval [0 1].
syms dt2;
f = (-2.4638*cos(dt2))-dt2 + 2.6628 - 0.0785;
fplot(f, [0 1])
yline(0)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/305639/image.png)
MATLAB is not able to solve it analytically (probably such a solution does not exist for this equation), so you will need to a numerical method, e.g., vpasolve() or fsolve(). An easy way to get the required solution is to give an initial guess such that it is closer to the required root. For example
f = @(dt2) (-2.4638*cos(dt2))-dt2 + 2.6628 - 0.0785;
sol = fsolve(f, 1)
Result
sol =
0.7002
更多回答(0 个)
另请参阅
类别
在 Help Center 和 File Exchange 中查找有关 Calculus 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!