MATLAB: Solving nonlinear equations in matlab

mathematicsMATLAB

hello,

I have problem about an equation. I would like to solve this eqution in matlab as input value P and I want to obtain output value S.

Do you make the necessary arrangements for the code to work in this order?

Thanks in advance !!

Best Answer

Use the Symbolic Math Toolbox:

syms S
P=10;
E=5;
V=0.33;
M=2;
K=1.5;
B=0.5;
H=0.3;
T=1;
Pfcn=((E*S)/(1-V^2)*M*K^2*B^2)*((H-S/2)*(H-S)*T+T^3);
Ssol = vpasolve(Pfcn == P)

producing:

Ssol =
 
                                         1.2272645680296059191773342534578
 - 0.16363228401480295958866712672892 - 1.5983944082554683248490550151884i
 - 0.16363228401480295958866712672892 + 1.5983944082554683248490550151884i

Related Solutions

MATLAB: Solving set of time-dependent differential equations using ode45

Hi,

try:

% Defining constants
Co = 0.16;
H = 3.9;
S = 380;
cb = 0.6;
ct = 0.6;
ab = 4*1.095*0.25;
at = 4*2.125*2.8;
ab_star = sqrt(2)*cb*ab;
at_star = sqrt(2)*ct*at;
A_star = sqrt(1/((1/ab_star^2)+(1/at_star^2)));
B = 0.4325;
Td = (Co^(1/2)*S*H^(4/3))/(A_star*B^(1/3));
Tf = S/(Co*B^(1/3)*H^(2/3));
mu = Td/Tf;
% Solving equations
tspan = [-10 60];
conds = [1; 1/Co];
[t, y] = ode45(@(t,x)odefcn(t,x,mu), tspan, conds);
plot(t,y(:,1),'-o',t,y(:,2), '-.')
function dpddel = odefcn(~,x, mu)
p = x(1);
del = x(2);
dpddel = zeros(2,1);
dpddel(1) = (1./sqrt(mu)).*sqrt(del*(1-p)) - sqrt(mu).*p.^(5/3);
dpdel(2) = sqrt(mu).*(1-p.^(5/3).*del)./(1-p);
end

Best regards

Stephan

MATLAB: Solving Differential Equation with initial conditions

You need to add the initial conditions as arguments to dsolve, and use the ‘double equal’ to assign them:

S_1s = dsolve(diff(S_1,t)==k_1*S_2^n/(K^n+S_2^n)-k_3*S_1-k_5*S_1, S_1(0)==0.0)
S_2s = dsolve(diff(S_2,t)==k_2+k_5*S_1-k_4*S_2, S_2(0)==0.6)

Best Answer

Related Solutions

MATLAB: Solving set of time-dependent differential equations using ode45

MATLAB: Solving Differential Equation with initial conditions

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