Solution of non linear equation

Question

Abdessami Jalled 2019-9-21

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/481445-solution-of-non-linear-equation

评论： Abdessami Jalled 2019-9-21

Hello,

Let tan(y)-c*tan(a*y)=0 be an equation.

question; is there any a and c such that this equation dos not have any solution. when i apply this code i obtain the empty set:

syms y c a

eq1 = tan(y)-c*tan(a*y);

gargar = solve(eq1)

then gargar = empty set. I think that this mean that there exists a and c such that our equation does not have any solution. But i cannot find this two reals a and c. please help.

4 个评论
显示 2更早的评论隐藏 2更早的评论

Bjorn Gustavsson 2019-9-21

在 MATLAB Online 中打开

Here's some sample code:

x = linspace(-4.7*pi,4.17*pi,3013); % Generate an array for the independent variable
a = 0.2; % some values for a 
c = 5;   % and c
plot(x,tan(x))
hold on
plot(x,c*tan(a*x))
axis([-15 15 -22.5 22.5])

The thing is that you should then think about what the curves imply - you have two piece-wise continuous functions, what has to be true for them never to be equal? This part is not a question

for computations - numerical or sybolic - but for thinking.

Abdessami Jalled 2019-9-21

thanks to you. what i want is that the to curves does not intersect in 0. and i think this is what i can see

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

darova 2019-9-21

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/481445-solution-of-non-linear-equation#answer_392894

在 MATLAB Online 中打开

Maybe there is no such a and c! I used isosurface to create several combinations:

clc,clear
cla
[a,c,y] = meshgrid(0:0.5:5);
f = tan(y)-c.*tan(a.*y);
p = patch( isosurface(a,c,y,f,0) ); % create surface when f=0
set(p,'FaceColor','red','EdgeColor','none');
daspect([1,1,1])
view(3); axis tight
camlight 
lighting gouraud
xlabel('a axis')
ylabel('c axis')
zlabel('y axis')