Invalid text character. Check for unsupported symbol, invisible character, or pasting of non-ASCII characters.

I really don't know what is the reason for this error. PLease help!

theta_dd(i)= (kP*r(i) +kD*r_dot(i) -(m*g*l+kP)*sin(theta(i)) -kD*theta_dot(i))/M;

[Manjunatha Manju]

What is the reason for this error , can you tell this.

[Walter Roberson]

The cause of this kind of problem is having an invisible character such as a zero-width space, or having accidentally used "smart-quotes" instead of regular quotes.

Answer 1

[James Browne]

It is impossible to debug your one line of code because I can't run it on my end due to undefined variables. However, if you copied and pasted that line of code into MATLAB, it is likely that there is some text character(s) in the line that you copied which matlab does not recognize.

If you did copy and paste the code, try typing it in by hand instead. Otherwise you will need to post the whole code before anyone can really help you.

[Nga Thede]

I thought the same at first so I retype it. However, I could be dead wrong, here is my full code

% Last MATLAB
clear all; clc;
l= 1;               %m lenght of the rod
m=5;                %kg mass of the pendulum
J= 1.25;            %kgm^2 at the pivot point
z= 0.707;           %damping ratio
wn=2*pi;            %rad/s bandwitch at z=0.707
M=J+m*l^2;          %Total inertia
g=9.81;
kD=2*z*wn*M         %Derivative control gain
kP=M*wn^2-m*g*l     %Proportional control gain
wd=wn*sqrt(1-z^2);  %imaginary part of s
% Part e
% Plot response with non-linear system
i=1;
tmax=100;
dt=0.001;
t(1)=0;
v(1)=0;             %start from rest
theta(1)=20*pi/180; %start from rest at 20 degrees
r(1)=0;             %desired position starting at 0 degree
r_dot(1)=0;
% Numerical intergration
theta_dot(i)=0;
for i=1:tmax
    theta_dd(i)= (kP*r(i) +kD*r_dot(i) -(m*g*l+kP)*sin(theta(i)) -kD*theta_dot(i))/M;​
    theta_dot(i+1)=theta_dot(i)+dt*theta_dd(i);
    theta(i+1)=theta(i)+dt*theta_dot(i);​
    t(1+i)=t(i)+dt;
    i=i+1;
end
figure
plot(t,theta,'--')
title('Theta vs Time ')
xlabel('Time (s)')
ylabel('Theta (rad)')

[Nga Thede]

The only line it said error is the line I posted above which I don't understand why cause I tried to retyped the whole line already and still saying the same thing.

[Walter Roberson]

Please attach the file that is having the problem, instead of pasting in the text.

Answer 2

[Walter Roberson]

    theta_dd(i)= (kP*r(i) +kD*r_dot(i) -(m*g*l+kP)*sin(theta(i)) -kD*theta_dot(i))/M;​

Right after the semi-colon you have char(8203) which us U+200b which is "zero width space".

Put your cursor on the semi-colon and press shift and right arrow several times until your cursor is positioned on the next line. That should highlight several characters. Type in ; and then return. This process should get rid of the zero-width space.

Answer 3

[Zeel Dhorajiya]

A={0.1/2+0.6/3+0.4/4+0.3/5+0.8/6} B={0.5/2+0.8/3+0.4/4+0.6/5+0.4/6} u=input(‘A’); v=input(‘B’); 

↑ Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax error. To construct matrices, use brackets instead of parentheses.

Please help me out

[Walter Roberson]

You used ʼ (right single quotation mark) instead of ' (vertical single quotation mark)

Answer 4

[Hem Ananth]

%Program for linear convolution
%to get the input sequence
n1=input('enter the length of input sequence');
n2=input('enter the length of impulse sequence');
x=input('enter the input sequence');
h=input('enter the impulse sequence');
%convolution operation
y=conv(x,h);
%to plot the signal
subplot(3,1,1);
stem(x);
ylabel('amplitude');
xlabel('n1....>');
title('input sequence')
subplot(3,1,2);
stem(h);
ylabel('amplitude');
xlabel('n2....>');
title('impulse signal')
subplot(3,1,3);
stem(y);
ylabel('amplitude');
xlabel('n3');
disp('the resultant signal is');y

[Walter Roberson]

Yes? What about the code?

Note that the use needs to enter [ and ] characters around the vector of data when you use input() that way. For example they would have to type in

[.3 .8]

complete with the [ and ]

[Scott]

n = 10;
A = tril(rand(n));
b = rand(n,1);
disp(’row-oriented:’)
tic
xR = RowSolve(A,b);
toc
disp(’column-oriented:’)
tic
xC = ColSolve(A,b);
toc
disp(’infinity norm of difference:’)
norm((xC - xR), Inf)
disp(’infinity norm of residual:’)
norm((b - A*xR), Inf)

[Stephen23]

@Scott: the problem with your code is already explained here: https://www.mathworks.com/matlabcentral/answers/516793-invalid-text-character-check-for-unsupported-symbol-invisible-character-or-pasting-of-non-ascii-c#comment_1608535

[Scott]

Awesome, thanks!