MATLAB: I’m trying to find the integral of dv and all variables have been defined. I get the error message ‘Dot indexing is not supported for variables of this type.’ or if I remove the dot I get ‘Not enough input arguments.’ Please show me the error. than

MATLABnumerical integration

theta1 = pi/4;

h0 = 30*10^-2;

a = 1*10^-2;

g = 9.81;

t_empty = (2*((tan((pi/2)-theta1))^2)*(h0^(5/2)))/(5*(a^2)*sqrt(2*g));

t = (0:0.01:t_empty/2);

ht = ((h0^(5/2))-(5*a^2*(sqrt(2*g).*t)/(2*(tan((pi/2)-theta1)^2))));

r = ((tan((pi/2)-theta1)).*ht);

dv = 1/3*pi*(r.^2).*((((-a)^2)*sqrt(2*g))/(tan((pi/2)-theta1)^2).*(ht.^(-3/2)));

integral(dv)

Best Answer

The erroir is that ‘dv’ must be defined as a function of one variable, and it is not defined as a function at all.

What variable do you want to integrate it with respect to?

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MATLAB: I am getting empty sym for vpasolve

Since thetac is an array of 15 elements, you are trying to solve a system of 15 incompatible equations, therefore, there is no answer. You should solve the equation for each value of thetac.

syms theta1 theta2 gama M l
eqn = theta1 == 2*atan((2*tan(theta2/2)*tan(gama/2 - theta2/2) + (4*tan(theta2/2)^2 - 4*M^2*tan(theta2/2)^2 - 4*M^2*tan(gama/2 - theta2/2)^2 - M^2*gama^2*l^2 - 8*M^2*tan(theta2/2)*tan(gama/2 - theta2/2) - 4*M^2*gama*l*tan(theta2/2) - 4*M^2*gama*l*tan(gama/2 - theta2/2) - M^2*gama^2*l^2*tan(theta2/2)^2*tan(gama/2 - theta2/2)^2 + 2*M^2*gama^2*l^2*tan(theta2/2)*tan(gama/2 - theta2/2) + 4*M^2*gama*l*tan(theta2/2)*tan(gama/2 - theta2/2)^2 + 4*M^2*gama*l*tan(theta2/2)^2*tan(gama/2 - theta2/2) + 4)^(1/2) - 2)/(2*tan(theta2/2) + 2*M*tan(gama/2 - theta2/2) + 2*M*tan(theta2/2) + M*gama*l - M*gama*l*tan(theta2/2)*tan(gama/2 - theta2/2)) - (2*tan(theta2/2)*tan(gama/2 - theta2/2))/(2*tan(theta2/2) + 2*M*tan(gama/2 - theta2/2) + 2*M*tan(theta2/2) + M*gama*l - M*gama*l*tan(theta2/2)*tan(gama/2 - theta2/2)));
F=1.06;
gama=pi/F;
thetac=0:0.2:gama;  
l=0.2181818;
M=0.960615;  
for k=1:numel(thetac)
    theta2=thetac(k);
    seqn = subs(eqn);
    sol(k) = vpasolve(seqn)
end
alpha_1=sol./thetac;
plot(thetac,alpha_1)

MATLAB: Graph of time against angle for multiple values of theta

You'll have only 2 curves:

a=1;
g=9.81*100;
theta = linspace(1,7,20)*pi/16;
hold on
for h0 = [30 40]
   tau = ((h0.^(5/2)).*2.*(tan((pi./2)-theta)).^2)./(5*a.^2.*sqrt(2*g));   
   plot(theta,tau)
end
hold off

Best Answer

Related Solutions

MATLAB: I am getting empty sym for vpasolve

MATLAB: Graph of time against angle for multiple values of theta

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