# Latex Failing for Big Linear System

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Koustubh Gohad on 31 May 2023
Edited: Koustubh Gohad on 1 Jun 2023
I'm trying to dynamically update an equation in a figure window, but latex seems to be failing for bigger matrices.
n = 20;
m = 1;
A = m*rand(n, n);
B = m*rand(n, 1);
C = A*B;
l = zeros(size(C));
figure; set(gca, 'visible', 'off')
f = gcf; f.Position = [185.8, 423.4, 1089.6, 420];
for i = 1:numel(B)
digits(2)
A_str = latex(sym(A(1:i, :), 'd'));
B_str = latex(sym(B, 'd'));
C_str = latex(sym(C(1:i), 'd'));
myEquation = strcat('$', A_str, B_str, ' = ', C_str, '$');
if i == 1
TT = text(0, 0.5, myEquation, 'Interpreter', 'latex', 'fontsize', 10);
else
TT.String = myEquation;
end
pause(0.5)
l(i) = strlength(myEquation);
end Warning: Error updating Text.

String scalar or character vector must have valid interpreter syntax:
$\left(\begin{array}{cccccccccccccccccccc} 0.55 & 0.77 & 0.11 & 0.74 & 0.72 & 0.21 & 0.98 & 0.73 & 0.37 & 0.8 & 0.85 & 0.61 & 0.013 & 0.04 & 0.2 & 0.14 & 0.36 & 0.42 & 0.1 & 0.8\\ 0.95 & 0.31 & 0.25 & 0.71 & 0.44 & 0.068 & 0.17 & 0.81 & 0.12 & 0.48 & 0.17 & 0.62 & 0.76 & 0.69 & 0.38 & 0.58 & 0.83 & 0.54 & 0.83 & 0.94\\ 0.26 & 0.2 & 0.81 & 0.25 & 0.26 & 0.37 & 0.39 & 0.14 & 0.18 & 0.93 & 0.23 & 0.18 & 0.17 & 0.36 & 0.91 & 0.27 & 0.56 & 0.86 & 0.5 & 8.9e-3\\ 0.45 & 0.85 & 0.85 & 0.8 & 0.94 & 0.22 & 0.67 & 0.84 & 0.93 & 0.31 & 0.8 & 0.54 & 0.91 & 0.85 & 0.98 & 0.16 & 0.15 & 0.2 & 0.14 & 0.68\\ 0.83 & 0.81 & 0.19 & 0.21 & 0.86 & 0.61 & 0.19 & 0.4 & 0.44 & 0.9 & 0.45 & 0.088 & 0.12 & 0.79 & 0.12 & 0.79 & 0.99 & 0.91 & 0.28 & 0.77\\ 0.95 & 0.81 & 0.39 & 0.12 & 0.4 & 0.78 & 0.51 & 0.79 & 0.5 & 0.17 & 0.56 & 0.41 & 0.38 & 0.36 & 0.091 & 0.27 & 0.75 & 0.23 & 0.96 & 0.7\\ 0.63 & 0.19 & 0.59 & 0.71 & 0.28 & 0.34 & 0.11 & 0.81 & 0.16 & 0.048 & 0.21 & 0.24 & 0.095 & 0.88 & 0.5 & 0.24 & 0.31 & 0.89 & 0.57 & 0.46\\ 0.092 & 0.4 & 0.018 & 0.35 & 0.97 & 0.49 & 0.74 & 0.49 & 0.75 & 0.34 & 0.64 & 0.26 & 0.87 & 0.35 & 0.87 & 0.2 & 0.74 & 0.38 & 0.95 & 0.46\\ 0.59 & 0.28 & 0.79 & 0.82 & 0.34 & 0.58 & 0.99 & 0.69 & 0.48 & 0.68 & 0.88 & 0.074 & 0.88 & 0.83 & 0.31 & 0.88 & 0.31 & 0.55 & 0.43 & 0.23\\ 0.53 & 0.23 & 0.92 & 0.38 & 0.73 & 0.96 & 0.58 & 0.62 & 0.83 & 0.41 & 0.64 & 0.76 & 0.97 & 0.21 & 0.78 & 0.66 & 0.77 & 0.78 & 0.46 & 0.96\\ 0.54 & 0.51 & 0.57 & 0.84 & 0.31 & 0.92 & 0.81 & 0.77 & 0.28 & 0.013 & 0.24 & 0.66 & 0.23 & 0.55 & 0.69 & 0.91 & 0.41 & 0.64 & 0.35 & 0.25\\ 0.26 & 0.094 & 0.97 & 3.0e-3 & 0.64 & 0.21 & 0.019 & 0.88 & 0.7 & 0.63 & 0.35 & 0.35 & 0.65 & 0.88 & 0.78 & 0.36 & 0.14 & 0.71 & 0.47 & 0.99\\ 0.79 & 0.29 & 0.38 & 0.36 & 0.91 & 0.085 & 0.85 & 0.46 & 0.21 & 0.44 & 0.048 & 0.76 & 0.37 & 0.72 & 0.33 & 0.46 & 0.71 & 0.38 & 0.58 & 0.73\\ 0.11 & 0.2 & 0.57 & 0.58 & 0.99 & 0.086 & 0.19 & 0.48 & 0.96 & 0.38 & 0.095 & 0.03 & 0.77 & 0.41 & 0.76 & 0.98 & 0.95 & 0.054 & 0.89 & 0.083\\ 0.6 & 0.09 & 0.87 & 0.89 & 0.25 & 0.6 & 0.083 & 0.36 & 0.44 & 0.42 & 0.92 & 0.94 & 0.54 & 0.53 & 5.0e-3 & 0.45 & 0.76 & 0.16 & 0.74 & 0.64\\ 0.43 & 0.34 & 0.49 & 0.72 & 0.15 & 0.71 & 0.077 & 0.92 & 0.37 & 0.99 & 0.6 & 0.41 & 0.21 & 0.7 & 0.72 & 0.96 & 0.35 & 0.37 & 0.86 & 0.59\\ 0.4 & 0.52 & 0.23 & 0.55 & 0.94 & 0.65 & 0.94 & 0.24 & 0.31 & 0.76 & 0.14 & 0.19 & 0.03 & 0.9 & 0.41 & 0.5 & 0.49 & 0.43 & 0.056 & 0.19\\ 0.99 & 0.75 & 0.075 & 0.58 & 0.37 & 0.59 & 0.019 & 0.76 & 0.14 & 0.68 & 0.86 & 0.94 & 0.84 & 0.44 & 0.093 & 0.36 & 0.45 & 0.46 & 0.49 & 0.13\\ 0.11 & 0.66 & 0.75 & 0.89 & 0.015 & 0.88 & 0.012 & 0.66 & 0.82 & 0.12 & 0.58 & 0.82 & 0.98 & 0.16 & 0.47 & 0.3 & 0.13 & 0.7 & 0.095 & 0.52\\ 0.56 & 0.047 & 0.42 & 0.41 & 0.093 & 0.37 & 0.63 & 0.41 & 0.64 & 0.74 & 0.53 & 0.14 & 0.76 & 0.11 & 0.59 & 0.2 & 0.97 & 0.12 & 0.55 & 0.32 \end{array}\right)\left(\begin{array}{c} 0.24\\ 0.57\\ 0.27\\ 0.46\\ 0.72\\ 0.47\\ 0.81\\ 0.21\\ 0.77\\ 0.43\\ 0.042\\ 0.99\\ 0.19\\ 0.37\\ 0.38\\ 0.67\\ 0.097\\ 0.15\\ 0.35\\ 0.73 \end{array}\right) =\left(\begin{array}{c} 4.7\\ 4.5\\ 3.0\\ 5.7\\ 4.6\\ 4.4\\ 3.2\\ 4.6\\ 4.7\\ 5.9\\ 4.9\\ 4.3\\ 4.9\\ 4.2\\ 4.4\\ 4.6\\ 4.4\\ 4.0\\ 4.3\\ 3.4 \end{array}\right)$
It works fine till n = 8, starts failing for the last iteration at n = 9. Any pointers to make it work for n = 20 would be greatly apprecaited. For n = 20, the number of characters in the equation string exceeds 1200 at i = 7, but the equation stops dislpaying at i = 3.
If copy the eqation string after the last iteration at n = 20 (i.e, n = 20, i = 20), and then insert -> equation -> latex equation and paste it (in a live script), it works as expected.
Walter Roberson on 31 May 2023
cla
probes = 1139:1:1140;
for K = 1:length(probes)
msg = "$" + repmat('x', 1, probes(K)-2) + "$";
text(.1, K*0.1, msg, 'interpreter', 'latex');
hold on
drawnow
end Warning: Error updating Text.

String scalar or character vector must have valid interpreter syntax:
$xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx$
So 1139 characters works, 1140 characters fails. At least for that set of characters.

Walter Roberson on 31 May 2023
Moved: Walter Roberson on 1 Jun 2023
cla
probes = 1:10;
base = repmat('\pi', 1, 300); %900 characters
for K = 1:length(probes)
msg = "$" + base + repmat('x', 1, probes(K)-2) + "$";
text(.1, K*0.1, msg, 'interpreter', 'latex');
hold on
drawnow
end Warning: Error updating Text.

String scalar or character vector must have valid interpreter syntax:
$\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pi\pixxxxxxxx$
3 character per \pi and repeat that 300 times and add in leading and trailing \$ gives us 902+1 and 902+2 working but 902+3 = 905 failing. But when I used repetitions of '. ' or 'x' then failure is at 1139 / 1140. Therefore the buffer size is not strictly by characters: something related to the content being rendered can trigger failure earlier.
Koustubh Gohad on 31 May 2023
Moved: Walter Roberson on 1 Jun 2023
Thank you!

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