Info

此问题已关闭。 请重新打开它进行编辑或回答。

Is there a function I can use to find out when a statement is true?

1 次查看（过去 30 天）
Adam Roudi
Adam Roudi 2020-4-23
关闭： MATLAB Answer Bot 2021-8-20
Hello,
I'm new to matlab.
Is there a function I can use to find out when a statement is true?
Simple example: for which "x" the equation is true.
1+x = 3
Can somebody help me?
Alex

此问题已关闭。

回答（2 个）

Sulaymon Eshkabilov
in your case, if ... else ... end structure should work very well.
Ameer Hamza
Ameer Hamza 2020-4-23
编辑：Ameer Hamza 2020-4-23
See this. It uses symbolic toolbox to solve the equations.
syms x
eq = 1+x == 3;
sol = solve(eq);
Result:
>> sol
sol =
2
See documentation of solve() function for more examples.
  3 个评论
显示 1更早的评论
Karan Mehta
Karan Mehta 2020-4-23
Hi Alexander
Can you please share the error message when you solve this equation. Also, in order to solve 1/(10^x * (10^x+1)), represent this in form of an equation ,eg. 1/(10^x*(10^x+1)) == "some value". Then it would work. Like i tried the following
>> syms z
>> eq = 1/(10^z * (10^z + 1)) == 10
eq =
1/(10^z*(10^z + 1)) == 10
>> sol = solve(eq)
sol =
log(- 35^(1/2)/10 - 1/2)/log(10)
log(35^(1/2)/10 - 1/2)/log(10)
Ameer Hamza
Ameer Hamza 2020-4-23
I got the same answer as Karan. But if you are using release older than R2020a, than it is possible that MATLAB didn't return a solution. It seems that MATLAB has made some improvements to the symbolic engine in the new release, and it is able to solve equations that were not possible before. In that case, you will need to rely on a numerical solution
eq = @(x) 1/(10^x*(10^x+1)) - 10;
sol = fsolve(eq, rand);
The downside is that it can only give one solution at a time.

此问题已关闭。

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by