Although you can use func2str() to convert the function handle to char array
sgtitle(sprintf(formatspec, func2str(q_array{k})));
but a more flexible solution is to create a seperate array for titles
q_array = {@(x)ones(size(x)); @(x) abs(x); @(x) x.^2; @(x) (1/3)+(2/3)*x.^2};
q_titles = {'ones(size(x))'; 'abs(x)'; 'x^2'; '(1/3)+(2/3)*x^2'};
for k =1:4
%Code that generates the plot for each loop
figure;
formatspec = 'Exact vs Scheme Plots for q({\\nu}) = %s';
sgtitle(sprintf(formatspec, q_titles{k}));
end
It gives more control over what appears in the title.
