Solution of radical equation

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Muhammad Hassaan Bin Tariq
Answered: Walter Roberson on 5 Oct 2022
I am solving the function but the values are not correct. Is there any problem with the coding?
%% Calculation_of_speed_ratio
A = 16000; % N
B = 125.66; % mm^2
for cycles = 10:10
t=cycles*0.1
syms f
fn = (0.044*A/B)*2.5*pi/3*((6.75*f/sqrt(45.5+f^2))+(32*f/sqrt(64+f^2))+(9.25*f/sqrt(85.5+f^2))) == 1216.7*sin(62.838*t);
x= vpasolve(fn,f)
plot(t,x,"o")
hold on
end
I have tried to set an interval but it is not giving solution e.g. [5,180]. It is returning an empty solution.
Thank you for the help in advance.
Regards

Answers (2)

Walter Roberson
Walter Roberson on 5 Oct 2022
We would not know if the code is correct as you did not show us the equations. We would, for example, not know whether the sin() term is meant to be dealing with degrees instead of radians.
If you
G=lhs(fn)-rhs(fn)
fplot(G, [0.01 180])
Then you will see that the equation is continuous monotonic and so has only one solution, which is around 0.08. it is therefore not a matter of vpasolve missing a root: vpasolve is giving back the only positive root.

Santosh Fatale
Santosh Fatale on 4 Oct 2022
Hi Muhammad,
I tried out the code shared by you and it looks like you need to declare variable f as Symbolic variable. You can do it in the same line where you are declairing variable "n_b".
  1 Comment
Muhammad Hassaan Bin Tariq
I missed the declaration while copying the code. I have declared the variable as I have edited the code in the question now.
Regards

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