Matlab code not computing

is anyone able to review my code and tell me why its not outputing correcrtly when i run it im not sure what errors i have

clear
p=-1;
z=-5;
K = 0.05:0.001:100;
a=K;
b=2*K.^2-p*K;
c=-z*K.^2;
root1 = (-b + sqrt(b.^2 - 4.*a.*c))./(2.*a);
root2 = (-b - sqrt(b.^2 - 4.*a.*c))./(2.*a);
root = root1;
K_corresponding = K;
decay_rate = real;
fprintf('The maximal imaginary part is: %f\n', max_imag_part);
fprintf('The corresponding value of K is: %f\n', K_corresponding);
fprintf('The decay rate is: %f\n', decay_rate);
figure
plot(real(root), imag(root));
scatter[real(root(max_index)], imag[root(max_index)], 'red'; 'filled');

Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters.

xlabel('Real Part');
ylabel('Imaginary Part');
title('Root Locus Plot');

[Stephen23]

scatter[real(root(max_index)], imag[root(max_index)], 'red'; 'filled');
%                                  ^               ^ should be parentheses 
%                           ^ what is this for?
%      ^ should be parenthesis, not square bracket

[lateef]

even afiter put in paranthesis my code still computes an error

scatter((real(root(max_index)), imag(root(max_index)), 'red'; 'filled';

Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters.

xlabel('Real Part');

Answer 1

[Alan Stevens]

The use of square brackets in the scatter function is not the only problem! Are you looking for something like this?

p=-1;
z=-5;
K = 0.05:0.001:100;
a=K;
b=2*K.^2-p*K;
c=-z*K.^2;
root1 = (-b + sqrt(b.^2 - 4.*a.*c))./(2.*a);
root2 = (-b - sqrt(b.^2 - 4.*a.*c))./(2.*a);
root = root1;

iroot = imag(root);
maximag = max(iroot);
max_index = find(iroot == maximag);
K_corresponding = K(max_index);
decay_rate = real(root(max_index));

fprintf('The maximal imaginary part is: %f\n',maximag);

The maximal imaginary part is: 1.936492

fprintf('The corresponding value of K is: %f\n', K_corresponding);

The corresponding value of K is: 2.000000

fprintf('The decay rate is: %f\n', decay_rate);

The decay rate is: -2.500000

figure
plot(real(root), imag(root));
hold on
scatter(real(root(max_index)), imag(root(max_index)), 'red', 'filled');
xlabel('Real Part');
ylabel('Imaginary Part');
title('Root Locus Plot');

[lateef]

yes thank you for the help

[Image Analyst]

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