Solve Command for Unknown Parameters

Dears,

How can I solve the following equation with MATLAB to get the value of the unknown parameter (beta):

7*exp(-0.008*beta)+0.008*sin(7*beta)-7*cos(7*beta)=0

I tried to use "SOLVE" command, but it give me every time: beta = 0

I don't know what's the incorrect in it.

Answer 1

[Steven Lord]

Let's see how your function looks in a neighborhood around y = 0.

f = @(beta) 7*exp(-0.008*beta)+0.008*sin(7*beta)-7*cos(7*beta);
fplot(f);
yticks(0);
grid on
ylim([-0.5 0.5]);

beta = 0 does look like a solution, but it is not the only solution. Calling fzero with different initial guesses may allow you to calculate those other solutions. If you think about your function you should be able to calculate roughly how far apart the local minima of your function should be, and that can inform your choice of starting points for fzero.

[Mostafa Sallam]

Thanks

Answer 2

[Walter Roberson]

If you vpasolve you can pass in a range to search over.