in matlab Unbalanced or unexpected parenthesis or bracket for definite integral

Question

I'm writing a program that can solve the equation of motion for an inverted pendulum. However, on the line "F=int ... ", I get an error saying "unbalanced or unexpected parenthesis or bracket". However, I checked it many times and it seems that the bracket/parenthesis are balanced. I'm guessing the error is coming from the part "s,tn-(n/2),tn+(n/2)", but I'm not sure why

function [ theta ] = Untitled( theta_o,omega_o )

nt=5001; %since (50-0)/.01 = 5000
dt = .01; % =H
H=.01;

theta_n = ones(nt,1);
theta_n(1)=0; %theta_o

omega_n = ones(1,nt);
omega_n(1)=-0.4; %omega_o

epsilon=10^(-6);
eta = epsilon*10;

t_o=0;

for n=1:4999
    tn=t_o+n*dt;
    F=int((422.11/eta)*exp[[5*(4*((eta*t-s-tn)^2)/eta^2)-1]^(-1)]*omega, s,tn-(n/2),tn+(n/2))
    theta_n(n+1) = theta_n(n) + h*F;
end

end

EDIT: I converted the [] into (), and now the error "Undefined function or variable 't'."

I converted the [] into (), and now get the error "Undefined function or variable 't'." — M K

Sheldon Sheldon · Accepted Answer · 2014-08-29T07:33:47

As @Molly pointed out in her comment the correct line should be:

F=int((422.11/eta)*exp((5*(4*((eta*t-s-tn)^2)/eta^2)-1)^(-1))*omega, s,tn-(n/2),tn+(n/2))

You cannot use square brackets [ and ] in Matlab like you would use them when writing maths on paper. Use round brackets ( and ) for all brackets in Matlab.

Square brackets are used to denote matrices in Matlab.

EDIT: That error is because in you code you have eta*t but you have not told MATLAB what t is. My guess is that it should be either tn or dt, or you need to define it as something:

t = %the correct value for t

But, I am not familiar with the problem you are trying to solve, so I suggest checking that you copied down the formula correctly.

in matlab Unbalanced or unexpected parenthesis or bracket for definite integral

1 Answers