plot curve with matlab

Hi. how can i plot this eq. to (qa-w)?

2502*cos(qa) - (6*w^2*cos(qa))/5 - (50873*w^2)/52500 + (123*w^4)/87500 - 357706/63=0

thank you

Answer 1

[Walter Roberson]

syms qa real
syms w
eqn = 2502*cos(qa) - (6*w^2*cos(qa))/5 - (50873*w^2)/52500 + (123*w^4)/87500 - 357706/63 == 0;

sol = solve(eqn);
sol = sol(isAlways(sol>0));  %4 solutions, 2 of which are complex, 1 is always negative for real qa

fplot(sol, [-pi pi])

[saman ahmadi]

Thank you for your answer dear Walter Roberson.

i ran sended code, but it has error. please see attachmented picture.

[Walter Roberson]

Which MATLAB release are you using? When I execute the code, I get something Gaussian curve with peak 49.6 at x = 0

[saman ahmadi]

I use matlab R2016a...

[Walter Roberson]

Okay, I will have to install that version; it will take a bit of time.

[Walter Roberson]

I just tested in R2016a, and had no problem with the code.

What shows up for

size(sol)
class(sol)

[saman ahmadi]

Thanks a lot dear Walter Roberson. At where should i copy them in last code that you send me?

[Walter Roberson]

Execute those in the command window after you run the code I posted earlier, and tell us what the results are. These are commands to help us debug the problem, not commands that will somehow fix the problem.