MATLAB: How to solve these two equations for ‘tau’ and ‘b’? All the other symbols are constants. Please help?

equationsymbolic

I've tried using the sysms command but not sure I'm getting the input formatting correct

Best Answer

Hi,

i used the isolate function instead of solve and found:

sol_tau =
tau == -(2778046668940015*R*g*sin((2*pi*(b + u0))/b0) + 281474976710656*b*b0*m*log(R/rc) - 2778046668940015*R*g*nu*sin((2*pi*(b + u0))/b0) - 140737488355328*b*b0*m*nu*log(R/rc))/(281474976710656*R*b0*pi*(nu - 1))
sol_b =
b == 0

by using these lines of code:

syms m b nu R rc tau g b0 u0
eqn1=(m*b/2)*((2-nu)/(1-nu))*R*log(R/rc)-tau*pi*R^2+(g*pi^2*R^2/b0)*sin(2*pi*(u0+b)/b0)==0;
eqn2=(m*b^2/4)*((2-nu)/(1-nu))*(1+log(R/rc))-2*pi*tau*R*b-g*pi*R*sin(pi*b/b0)*sin(pi*(2*u0+b)/b0)==0;
sol_tau = simplifyFraction(isolate(eqn1,tau))
eqn2_new = simplifyFraction(subs(eqn2,tau,rhs(sol_tau)));
sol_b = simplifyFraction(isolate(eqn2_new,b))

I did not check if you have typos in your equations...

Best regards

Stephan

Related Solutions

MATLAB: How can we solve only for t1 variable in the equation P=R1 which has multiple variables such as t2 t3. Which is possible mathematically.

With respect to

syms t1 t2 t3
R1 = [
    cos(t2)*cos(t3) - sin(t2)*sin(t3),  - cos(t2)*sin(t3) - cos(t3)*sin(t2), 0, 10*cos(t2);
    (7344817515977723*cos(t2)*sin(t3))/9223372036854775808 + (7344817515977723*cos(t3)*sin(t2))/9223372036854775808, (7344817515977723*cos(t2)*cos(t3))/9223372036854775808 - (7344817515977723*sin(t2)*sin(t3))/9223372036854775808, 9007196398844849/9007199254740992, (36724087579888615*sin(t2))/4611686018427387904 + 45035981994224245/4503599627370496;
     - (9007196398844849*cos(t2)*sin(t3))/9007199254740992 - (9007196398844849*cos(t3)*sin(t2))/9007199254740992,       (9007196398844849*sin(t2)*sin(t3))/9007199254740992 - (9007196398844849*cos(t2)*cos(t3))/9007199254740992, 7344817515977723/9223372036854775808, 36724087579888615/4611686018427387904 - (45035981994224245*sin(t2))/4503599627370496;
     0, 0, 0, 1];
P = [
     (433*cos(t1))/500, -cos(t1)/2, sin(t1),  0;
    -(433*sin(t1))/500,  sin(t1)/2, cos(t1), 0;
    -1/2, 433/500, 0, 0;
    0,  0, 0, 1];

there is no possible solution for R1 == P.

Compare R1(3,3) = 7344817515977723/9223372036854775808 to P(3,3) = 0. These are constants but do not equal each other, so it is not possible to find t1, t2, t3 that will make the matrices equal.

MATLAB: How to solve system of equations in Matlab R2018b

syms W13sol W14sol W20sol 
W15=6;  % an example of datas
W12=8; 
tau01=9;
tau02=10;
tau03=11;
eqtau01=((W14sol-W20sol)/(W15-W20sol)==tau01); %equazione di willis tra 15 e 14
eqtau02=((W14sol-W20sol)/(W12-W20sol)==tau02); %equazione di Willis tra 14 e 12
eqtau03=((W13sol-W20sol)/(W12-W20sol)==tau03); %equazione di Willis tra 13 e 12
solT=solve(eqtau01,eqtau02,eqtau03,W13sol,W14sol,W20sol);
solT.W13sol % to view solution 
%or the below in one line to view all the solutions at once
[W13sol,W14sol,W20sol]=solve(eqtau01,eqtau02,eqtau03,W13sol,W14sol,W20sol); % if you are lazy to do the next step as mentioned above

Best Answer

Related Solutions

MATLAB: How can we solve only for t1 variable in the equation P=R1 which has multiple variables such as t2 t3. Which is possible mathematically.

MATLAB: How to solve system of equations in Matlab R2018b

Related Question